Vulcanisable compositions based on epoxy group-containing nitrile rubbers

ABSTRACT

There are provided novel vulcanizable compositions based on optionally fully or partly hydrogenated nitrile rubbers containing epoxy groups, specific basic crosslinkers and crosslinking accelerators, as a result of which the use of conventional crosslinkers, such as sulphur in particular, is no longer required. The vulcanizates producible therefrom possess very good compression sets at room temperature, 100° C. and 150° C., and additionally exhibit high tensile stress combined with good elongation at break.

The invention relates to vulcanizable compositions based on optionallyfully or partly hydrogenated nitrile rubbers containing epoxy groups,and specific crosslinkers, to a process for production thereof, to aprocess for production of vulcanizates therefrom, to the vulcanizatesthus obtained, and to fully or partly hydrogenated nitrile rubberscontaining epoxy groups.

Nitrile rubbers, often also abbreviated to “NBR”, are understood to meanrubbers which are co- or terpolymers of at least one α,β-unsaturatednitrile, at least one conjugated diene and optionally one or morefurther copolymerizable monomers. Hydrogenated nitrile rubbers (“FINER”)are understood to mean corresponding co- or terpolymers in which all orsome of the C═C double bonds of the copolymerized diene units have beenhydrogenated.

For many years, both NBR and HNBR have occupied an established positionin the specialty elastomers sector. They possess an excellent profile ofproperties, in the form of excellent oil resistance, good heatstability, excellent resistance to ozone and chemicals, the latter beingeven more pronounced in the case of HNBR than in the case of NBR, NBRand HNBR also have very good mechanical and performance properties. Forthis reason, they are widely used in a wide hey variety of differentfields of use, and are used, for example, for production of gaskets,hoses, belts and damping elements in the automotive sector, and also forstators, well seals and valve seals in the oil production sector, andalso for numerous parts in the electrical industry, mechanicalengineering and shipbuilding. A multitude of different types arecommercially available, and these feature, according to the applicationsector, different monomers, molecular weights, polydispersities andmechanical and physical properties. As well as the standard types, thereis increasing demand particularly for specialty types featuring contentsof specific termonomers or particular functionalizations.

In practical use of (H)NBR rubbers, the vulcanization of the rubbers isalso becoming increasingly important, i.e. particularly the crosslinkersystem and the vulcanization conditions. Thus, in addition to theconventional rubber crosslinking systems based on peroxides or sulphur,which have already been in existence for several decades, the last fewyears have seen developments of various new concepts for alternativecrosslinking. Such crosslinking concepts also include polymers which,due to functional groups, are not amenable to all forms of crosslinkingand crosslinking agents and therefore constitute a particular challenge.

U.S. Pat. No. 4,094,831 describes the crosslinking of co- or terpolymersof conjugated C₄-C₁₀-conjugated dienes, optionally additionallyC₂-C₁₄-olefins and a monomer comprising epoxy groups, by using mono- andpolyamines, mono- and polyanhydrides, and mono- and polycarboxylicacids. Acrylonitrile is not used as a monomer for preparation of theseco- or terpolymers.

Polymer 46 (2005) 7632-7643 describes the preparation of glycidylmethacrylate-grafted acrylonitrile-butadiene-styrene copolymers(ABS-g-GMA) by emulsion polymerization. This ABS-g-GMA polymer issubsequently used to produce a blend with polybutylene terephthalate(PBT). Good dispersibility of the ABS-g-GMA particles in the PBT matrixis reported, and this is attributed to a reaction between thecarboxyl/hydroxyl groups of the PBT chain ends and the epoxy groups ofthe GMA units at the interface.

WO-A-02/46254 describes functionalized quaterpolymers based onconjugated dienes, vinyl-substituted aromatic compounds, olefinicallyunsaturated nitriles and monomers containing hydroxyl groups orcontaining epoxy groups, rubber mixtures based thereon and use thereoffor production of all kinds of rubber mouldings. The rubber mixturesmay, according to page 8 line 27 and page 9 lines 18-19, comprise thecustomary crosslinkers. Examples of crosslinkers mentioned at page 9lines 28 to 30 include, for example, elemental sulphur and sulphurdonors, such as polysulphides, for example dithiocarbamates and thiurampolysulphides. It is stated in general terms that, in addition to thecrosslinker, it is possible to use vulcanization accelerators (e.g.amines, guanidines, thioureas, thiazoles, thiurams, dithiocarbamates,xanthogenates and sulphonamides) (page 9 lines 25, 26). It is specifiedthat these additives are used in customary amounts (page 9 line 21).Whether, and in what way, the compression set of corresponding mouldingsat high temperatures and in the case of prolonged stress can beinfluenced by crosslinking systems of specific composition cannot beinferred from WO-A-2002/46254. According to the examples ofWO-A-02/46254, the sulphur crosslinker is used in amounts of 1.5 partsby weight, based on 100 parts by weight of all rubbers present in thevulcanizable mixture.

JP-A-2005/120143 relates to rubbers containing repeat units of anunsaturated nitrile, of at least one acrylic ester, of an epoxy monomer,of at least one nonconjugated cyclic polyene and optionally of furtherunsaturated monomers, for example butadiene. Crosslinking agentsspecified are sulphur, organic peroxides or metal salts of aromatic oraliphatic carboxylic acids or anhydrides thereof.

European Polymer Journal 37 (2001), pages 547-557 describes glycidylmethacrylate-grafted nitrile rubbers which are used as compatibilizersin polymer mixtures. They are prepared by peroxidically initiated graftreaction of glycidyl methacrylate onto the NBR rubber.

EP-A-0 160 399 describes quaterpolymers based on a cyano-substitutedalkyl (meth)acrylate, an alkyl acrylate, a crosslinkable monomer and afurther unsaturated monomer for applications particularly in theautomotive sector, where a high use temperature, good stability to ozoneand acidic petroleum or gasohol is required. The crosslinkable monomerused may also be a monomer comprising epoxy groups. Crosslinking agentsspecified in the case of unsaturated polymers include sulphur, sulphurdonors or peroxides, and in the presence of epoxide groups thecrosslinking thereof by polyamines and salts thereof, ammoniumcompounds, or in combination with conventional crosslinking systems.

Polymer 40 (1999), pages 3665-3676 describes using a specific methylmethacrylate/glycidyl methacrylate/ethyl acrylate terpolymer (MGE) toincrease the compatibility of polybutylene terephthalate (PET) withacrylonitrile-butadiene-styrene terpolymers (ABS) in blends. It isstated that residual amounts of acids remaining in the ABS prepared byemulsion polymerization can lead to crosslinking reactions involving theepoxy functionalities of MGE. It is explained that nitrile and epoxidefunctions can form oxazolines as a subsequent reaction, or nitriles canbe hydrolysed to give carboxyl groups, which can likewise react withepoxy groups. Evidence is presented that these crosslinkings have anadverse effect on the mechanical properties of the ABS and of the blend,and it is concluded, moreover, that strong acids can cause the formationof a gel or of a crosslinked network in the SAN matrix, provided thatthe MGE terpolymer is present.

U.S. Pat. No. 5,334,666 A describes vulcanizable elastomer compositionscontaining epoxy groups. These compositions comprise an elastomercontaining epoxy groups and a crosslinker system comprising (1) anorganic compound having two structural elements —C(═X)—NH—C(═Y)— inwhich X and Y are each independently oxygen or sulphur, and (2) aquaternary compound selected from quaternary ammonium salts andquaternary phosphonium salts. The organic compound (1) is preferably aheterocyclic, aromatic or aliphatic compound. These heterocycliccompounds preferably include parabanic acid, alloxan, alloxantin,alloxan 5-oxime, barbituric acid, 5-hydroxybarbituric acid,5-benzalbarbituric acid, 5-aminobarbituric acid,5-hydroxyiminobarbituric acid, 5,5-diethylbarbituric acid,5-ethyl-5-phenylbarbituric acid, 5-(1-methylbutyl)-5-(allyl)barbituricacid, 5,5-diallylbarbituric acid, isocyanuric acid and pseudouric acid,and compounds in which the oxygen in the aforementioned heterocycliccompounds has been replaced by a sulphur atom, e.g. 2,4-dithiobarbituricacid and 2-thiobarbituric acid. Preferred aromatic compounds arepyromellitic diimide, mellitic triimide and 1,4,5,8-naphthalic diimide,and the corresponding thioimides. Examples of aliphatic compounds aretriuret, 1-methyltriuret, 1,1-diethyltriuret and tetrauret, and thecorresponding thioureas. In example 5, a butadiene/acrylonitrilecopolymer elastomer containing epoxy groups is vulcanized with the aidof a crosslinker. According to table 10 of U.S. Pat. No. 5,334,666, thecrosslinkers used are mixtures of isocyanuric acid (1.8 phr) and OTMeABr(octadecyltrimethylammonium bromide) (1.6 phr), 5,5-diethylbarbituricacid (2.5 phr) and OTMeABr (1.6 phr) or of isocyanuric acid (1.8 phr)and CePyBr (cetylpyridinium bromide) (1.4 phr). According to thecomparative example, exclusively 1 phr of ammonium benzoate is used asthe crosslinker.

JP 01-113477 A relates to an adhesive which is obtained by adding acrosslinker (e.g. nadic methyl anhydride, i.e.methyl-5-norbornene-2,3-dicarboxylic anhydride) to a base componentcomprising 100 parts by weight of an epoxy resin, 1 to 40 parts byweight of a rubber which is obtained by grafting polymerizable monomerscontaining epoxy groups (e.g. glycidyl methacrylate) onto the rubber(e.g. acrylonitrile-butadiene copolymer), and 1 to 20 parts by weight offine solid rubber particles, obtainable by dispersing a typically liquidor dissolved solid epoxy resin in a liquid rubber, and then vulcanizingthe rubber. The use of conventional crosslinkers, such as sulphur andsulphur compounds, is described, as is the option of using thiurams,xanthogenates, thioureas, dithiocarbonates as accelerators.

US 2010/0152365 A1 discloses a carboxylic acid-modified nitrilecopolymer latex which is used for production of mouldings and which, dueto the absence of sulphur and a vulcanization accelerator, cannottrigger any allergic reactions and has further positive properties. As acrosslinkable unsaturated monomer, the copolymer latex may containglycidyl (meth)acrylate. The crosslinker used may be an ioniccrosslinker which does not trigger any allergic reactions. Claim 16 inUS 2010/0152365 A1 specifies zinc oxide as an ionic crosslinker. US2010/0152365 A1 does not describe, however, whether and in what wayselection of a suitable crosslinker system can improve compression setat relatively high temperatures and for long stress periods.

U.S. Pat. No. 4,650,834 discloses epoxy-containing elastomercompositions which, as well as an elastomer (1) containing epoxy groups,comprise a polycarboxylic acid having at least two carboxyl groups inthe molecule, (2) a quaternary compound selected from the groupconsisting of quaternary ammonium salts and quaternary phosphoniumsalts, and (3) a processing aid. The mixture of components (1) and (2)is used as a crosslinker. In example 5, a terpolymer based on butadiene,acrylonitrile and glycidyl methacrylate is vulcanized with the aid of acrosslinker system. The crosslinker system used iscetyltrimethylammonium bromide (2 phr)/tetradecanedioic acid (2.2 phr)or tetrabutylphosphonium bromide (1.5 phr)/tetradecanedioic acid (2.2phr).

It was an object of the present invention to provide a thermally stablecrosslinking system for nitrile rubbers containing epoxide groups, byvirtue of which it is possible to substantially reduce or entirely avoidthe use of peroxidic or sulphur-containing crosslinkers in vulcanizablecompositions based on such nitrile rubbers containing epoxy groups, andto further improve compression sets at high temperatures and especiallyfor long stress periods.

The novel crosslinking system shall avoid the disadvantages of theexisting crosslinkers, be easy to introduce into the vulcanizablenitrile rubber compositions and enable a crosslinking reaction underuncomplicated conditions, without any occurrence of side reactions, forexample acid-base reactions with further additives in the vulcanizablecomposition, for example ageing stabilizers. The crosslinkers usedshould have good handling qualities and should be usable equallysuccessfully for nitrile rubbers containing epoxide groups and forhydrogenated nitrile rubbers containing epoxide groups. The thuscrosslinked (H)NBR rubbers containing epoxide groups shall as far aspossible have good to very good compression set values, especially athigh temperatures and in long-term use, exhibit a good combination ofelongation at break and tensile strength, and hence offer an alternativeto or improvement over the conventional systems.

The object is achieved by a vulcanizable composition comprising

-   (i) at least one optionally fully or partly hydrogenated nitrile    rubber containing epoxy groups and comprising repeat units derived    from at least one conjugated diene, at least one α,β-unsaturated    nitrile and optionally one or more further copolymerizable monomers,    but not from a nonconjugated cyclic polyene,-   (ii) at least one Lewis and/or Brønsted base as a crosslinker, and-   (iii) at least one crosslinking accelerator selected from the group    consisting of thiurams, xanthogenates, thioureas, dithiocarbamates    and carbamates,    where the Lewis and/or Brønsted base (ii) must be different from the    defined group of crosslinking accelerators (iii), and also    crosslinkers other than those mentioned in (ii) are present in the    vulcanizable composition only in an amount less than 2.5 pans by    weight based on 100 parts by weight of the optionally fully or    partly hydrogenated nitrile rubber (i) containing epoxy groups, and    crosslinking accelerators other than those mentioned in (iii) are    present only in an amount of less than 2.5 parts by weight based on    100 parts by weight of the optionally fully or partly hydrogenated    nitrile rubber (i) containing epoxy groups.

The proviso that the Lewis and/or Brønsted base (ii) must be differentfrom the defined group of crosslinking accelerators (iii) applies to allfurther embodiments, even if not mentioned explicitly for each case.

It has been found that, surprisingly, in the case of the inventive useof the aforementioned crosslinkers (ii) in combination with at least onecrosslinking accelerator (iii) in the vulcanizable composition,thermally stable networks can be formed. The crosslinking orvulcanization is catalysed by the Lewis and/or Brønsted base(s) and thecrosslinking accelerator (iii).

The amount of other crosslinkers used, for example sulphur, sulphurdonors and peroxides and other crosslinking accelerators can bedrastically reduced, and it may even be possible to dispense entirelytherewith.

In one embodiment, the vulcanizable composition comprises

-   -   crosslinking accelerators other than those mentioned in (iii)        only in an amount of less than 2.5 parts by weight based on 100        parts by weight of the optionally fully or partly hydrogenated        nitrile rubber (i) containing epoxy groups and, at the same        time,    -   crosslinkers other than those mentioned in (ii) up to a maximum        amount of 2.3 parts by weight, preferably up to a maximum amount        of 2.25 parts by weight, more preferably up to a maximum amount        of 2 parts by weight, even more preferably up to a maximum        amount of 1.5 parts by weight, especially up to a maximum amount        of 1 part by weight, especially preferably up to a maximum        amount of 0.5 part by weight and very especially preferably up        to a maximum amount of 0.4 part by weight, also based in each        case on 100 parts by weight of the optionally fully or partly        hydrogenated nitrile rubber (i) containing epoxy groups.

In a further embodiment, the vulcanizable composition comprises

-   -   crosslinkers other than those mentioned in (ii) only in an        amount of less than 2.5 parts by weight based on 100 parts by        weight of the optionally fully or partly hydrogenated nitrile        rubber (i) containing epoxy groups and, at the same time,    -   crosslinking accelerators other than those mentioned in (iii) up        to a maximum amount of 2.3 parts by weight, preferably up to a        maximum amount of 2.25 parts by weight, more preferably up to a        maximum amount of 2 parts by weight, even more preferably up to        a maximum amount of 1.5 parts by weight, especially up to a        maximum amount of 1 part by weight, especially preferably up to        a maximum amount of 0.5 part by weight and very especially        preferably up to a maximum amount of 0.4 part by weight, also        based in each case on 100 parts by weight of the optionally        fully or partly hydrogenated nitrile rubber (i) containing epoxy        groups.

In a further embodiment, the vulcanizable composition comprises

-   -   crosslinkers other than those mentioned in (ii) only in an        amount of up to 1 part by weight based on 100 parts by weight of        the optionally fully or partly hydrogenated nitrile rubber (i)        containing epoxy groups and, at the same time,    -   crosslinking accelerators other than those mentioned in (iii) up        to a maximum amount of 2.3 parts by weight, preferably up to a        maximum amount of 2.25 parts by weight, more preferably up to a        maximum amount of 2 parts by weight, even more preferably up to        a maximum amount of 1.5 parts by weight, especially up to a        maximum amount of 1 part by weight, especially preferably up to        a maximum amount of 0.5 part by weight and very especially        preferably up to a maximum amount of 0.4 part by weight, also        based in each case on 100 parts by weight of the optionally        fully or partly hydrogenated nitrile rubber (i) containing epoxy        groups.

In a further embodiment, the vulcanizable composition comprises, basedin each case on 100 parts by weight of the optionally fully or partlyhydrogenated raffle rubber (i) containing epoxy groups,

-   -   crosslinkers other than those mentioned in (ii) up to a maximum        amount of 2.3 parts by weight and, at the same time,        crosslinking accelerators other than those mentioned in (iii) up        to a maximum amount of 2.3 parts by weight,    -   preferably crosslinkers other than those mentioned in (ii) up to        a maximum amount of 2.25 parts by weight and, at the same time,        crosslinking accelerators other than those mentioned in (iii) up        to a maximum amount of 2.25 parts by weight,    -   more preferably crosslinkers other than those mentioned in (ii)        up to a maximum amount of 2 parts by weight and, at the same        time, crosslinking accelerators other than those mentioned        in (iii) up to a maximum amount of 2 parts by weight,    -   even more preferably crosslinkers other than those mentioned        in (ii) up to a maximum amount of 1.5 parts by weight and, at        the same time, crosslinking accelerators other than those        mentioned in (iii) up to a maximum amount of 1.5 parts by        weight,    -   especially crosslinkers other than those mentioned in (ii) up to        a maximum amount of 1 part by weight and, at the some time,        crosslinking accelerators other than those mentioned in (iii) up        to a maximum amount of 1 part by weight,    -   especially preferably crosslinkers other than those mentioned        in (ii) up to a maximum amount of 0.5 part by weight and        crosslinking accelerators other than those mentioned in (iii) up        to a maximum amount of 0.5 part by weight,    -   very especially preferably crosslinkers other than those        mentioned in (ii) up to a maximum amount of 0.4 part by weight        and crosslinking accelerators other than those mentioned        in (iii) up to a maximum amount of 0.4 part by weight and    -   even more especially preferably absolutely no crosslinkers other        than those mentioned in (ii) and absolutely no crosslinking        accelerators other than those mentioned in (iii).

In a further embodiment of the vulcanizable composition, the sum ofcrosslinkers other than those mentioned in (ii) and crosslinkingaccelerators other than those mentioned in (iii) is at a maximum amountof 2.5 parts by weight, preferably at a maximum amount of 2.25 parts byweight, more preferably at a maximum amount of 2 parts by weight, evenmore preferably at a maximum amount of 1.5 parts by weight, especiallyat a maximum amount of 1 part by weight, especially preferably at amaximum amount of 0.5 part by weight and very especially preferably at amaximum amount of 0.4 part by weight, based on 100 parts by weight ofthe optionally fully or partly hydrogenated nitrile rubber (i)containing epoxy groups.

All aforementioned embodiments preferred in any way, with regard to thecorrespondingly specified reduced maximum contents for the presence ofcrosslinkers other than those mentioned in (ii) and the presence ofcrosslinking accelerators other than those mentioned in (iii), alsoapply to the preferred embodiments of the vulcanizable composition whichare also specified in the context of this application, having achemically more specific definition of components (i), (ii) and/or(iii).

If the vulcanizable composition also comprises one or more rubbers otherthan those mentioned in (i), all aforementioned maximum amounts and theembodiments thereof preferred in any way for crosslinkers other thanthose mentioned in (ii) and crosslinking accelerators other than thosementioned in (iii) are based on 100 parts by weight of the sum of theoptionally fully or partly hydrogenated nitrile rubber (i) containingepoxy groups and all other rubbers present in the composition.

Compared to vulcanizable compositions not including any crosslinkingaccelerator (iii) aside from the crosslinker (ii), the inventivevulcanizable compositions have the advantage of leading to vulcanizateshaving improved, i.e. lower, compression set, especially at highertemperatures and often within shorter crosslinking times.

It is possible that the vulcanizable composition does not comprise anyother crosslinker at all apart from the crosslinker(s) (ii) or anyfurther crosslinking accelerator apart from those mentioned in (iii). Inaddition, it is also possible to dispense with the use of the knowncocatalysts, and so heavy metal-free vulcanizates are obtainable. In oneembodiment, the vulcanizable composition does not comprise anycocatalysts, more particularly any heavy metal-containing cocatalysts.In a further embodiment, the inventive vulcanizable composition does notcomprise any crosslinker other than the crosslinker(s) (ii) or, at thesame time, any crosslinking accelerator other than that/those mentionedin (iii), or, in addition, any cocatalysts, more particularly any heavymetal-containing cocatalysts. The crosslinking density can be controlledand adjusted within wide ranges through the proportion of epoxy groupsin the nitrile rubber. The resulting vulcanizates exhibit excellentcompression set values at temperatures from room temperature up totemperatures of 150° C.

In one embodiment, the nitrile rubber may also be a fully or partlyhydrogenated nitrile rubber in which some or all of the C═C double bondspresent in the repeat units of the nitrile rubber have beenhydrogenated.

Crosslinker (ii): Lewis and/or Brønsted Base(s)

The Lewis or Brönsted bases used may be any suitable inorganic ororganic bases, but these must not be selected from the list of compoundscovered by the defined group of vulcanization accelerators (iii) fallen.It has been found to be useful to use Lewis bases which are electronpair donors, or Brønsted bases which are proton acceptors and have apK_(B) in the range from −12 to +13, preferably in the range from −11 to+12, more preferably in the range from −10.5 to +10, even morepreferably in the range from −10 to +9.5 and especially in the rangefrom −10 to +8.

The inventive vulcanizable composition preferably comprises, ascrosslinker (ii), at least one inorganic or organic Brønsted and/orLewis base.

Lewis Bases:

Any of the Lewis bases used which is an electron pair donor may be

-   (a) a transition metal or semimetal, aluminium, gallium, indium,    tin, thallium or lead in elemental form or-   (b) an alkyl or aryl compound, ester, salt, complex or oxide of the    alkali metals, alkaline earth metals, transition metals or    semimetals, of aluminium, gallium, indium, tin, thallium, lead,    nitrogen, oxygen or phosphorus.

Any of the Lewis bases used which is an electron pair donor maypreferably be

-   (a) a transition metal or semimetal, aluminium, indium or tin in    elemental form, or-   (b) an alkyl or aryl compound, ester, salt, complex or oxide of the    alkali metals, alkaline earth metals, transition metals or    semimetals, of aluminium, indium, tin, nitrogen, oxygen or    phosphorus.

The Lewis base(s) used are more preferably crown ethers, especially12-crown-4, cryptands, especially [2.2.2]-cryptand, ammonia,tetraalkylammonium salts, especially tetraalkylammonium bromides,benzyltrialkylammonium salts, tetraalkylphosphonium salts,benzyltrialkylphosphonium salts, triphenylphosphine, sodium cyanide orpotassium cyanide, sodium iodide, bipyridine, phenanthroline,tetrahydrofuran, cyclooctadiene, hydrazine or diethyl ether.

Brønsted Bases:

The Brønsted base(s) used are preferably those selected from the groupconsisting of sulphates, sulphites, sulphides, phosphates, carbonates,substituted or unsubstituted amities, substituted or unsubstituted,aromatic or nonaromatic nitrogen-containing organic heterocycles,substituted or unsubstituted urea derivatives, guanidines andderivatives thereof, hydroxides of alkali metals or alkaline earthmetals, salts of inorganic or organic sulphonic acids, carboxylic acidsand phosphonic acids, the mono- or diesters thereof, and organometalliccompounds of the alkali metals lithium, sodium and potassium.

Preferred carbonates are sodium carbonate, potassium carbonate, calciumcarbonate and lithium carbonate.

Preferred substituted or unsubstituted amines are ammonia,triethylamine, diisopropylamine and triethanolamine.

Preferred substituted or unsubstituted, aromatic or nonaromaticnitrogen-containing organic heterocycles are pyridine,1,8-diazabicyclo[5.4.0]undec-7-ene, 1,4-diazabicyclo[2.2.2]octane,tetramethylethylenediamine, pyrrolidine, pyrazole, piperidine, pyrroleand imidazole.

Preferred substituted or unsubstituted urea derivatives are urea,biuret, dimethylurea and N,N′-dimethylpropyleneurea.

Preferred salts of sulphonic acids are sodium alkylbenzylsulphonatesespecially sodium dodecylbenzylsulphonate.

Preferred salts of phosphonic acids are sodium or potassium salts of1-hydroxyethane(1,1-diphosphonic acid), aminotrimethylenephosphonic acidand ethylenediaminetetra(methylenephosphonic acid).

Preferred salts of the carboxylic acids are sodium or potassium salts ofascorbic acid, acetic acid, propionic acid, acrylic acid, fumaric acid,maleic acid, benzoic acid, abietic acid and saturated and unsaturatedfatty acids, for example stearic acid and oleic acid.

Preferred organometallic compounds of the elements lithium, sodium andpotassium are sodium ethoxide, sodium methoxide, butyllithium, lithiumdiisopropylamide and potassium ethoxide.

Component (iii): Crosslinking Accelerator

In the vulcanizable compositions of this invention, the component (iii)used is at least one crosslinking accelerator selected from the groupconsisting of thiurams, xanthogenates, thioureas, dithiocarbamates andcarbamates.

In a preferred embodiment, the vulcanizable composition comprises, ascomponent (iii), at least one crosslinking accelerator selected from thegroup consisting of thiurams, xanthogenates, dithiocarbamates andcarbamates.

Their vulcanization performance is often so rapid that they arevirtually not used in conventional crosslinking systems due to theirreactivity.

Useful thiurams preferably include a thiuram monosulphide, thiuramdisulphide or thiuram polysulphides. Examples of preferred thiurams aretetramethylthiuram disulphide (TMTD), tetramethylthiuram monosulphide(TMTM), tetraethylthiuram disulphide (TETD), dipentamethylenethiuramtetrasulphide (DPTT), dipentamethylenethiuram hexasulphide (DPTH),dipentamethylenethiuram monosulphide (DPTM), dipentamethylenethiuramdisulphide (DPTD), N,N′-diethyl-N,N′-diphenylthiuram disulphide (EPTDM)or dimethyldiphenylthiuram disulphide (MPTD).

Useful xanthogenates preferably include the alkali metal or zinc saltsof the xanthogenates and the arylguanidine xanthogenates. Examples ofpreferred xanthogenates are arylguanidinium xanthogenates,bisxanthogenates or polyxanthogenates, zinc isopropylxanthogenate (ZIX)or the water-soluble sodium salt thereof (NaIX).

Useful thioureas preferably include ethylenethiourea (ETU),diphenylthiourea (DPTU), 1,3-di-o-tolylthiourea (DTTU) ordiethylthiourea (DETU).

Useful dithiocarbamates preferably include the metal and ammoniumdithiocarbamates. Examples of preferred dithiocarbamates are zincdimethyldithiocarbamate (ZDMC), zinc diethyldithiocarbamate (ZDEC), zincdibutyldithiocarbamate (ZDBC), zinc ethylphenyldithiocarbamate (ZEPC),zinc dibenzyldithiocarbamate (ZDBC), zinc pentamethylenedithiocarbamate(ZPD), zinc N-pentamethylenedithiocarbamate (Z5MC), zinclupetidinedithiocarbamate (ZLD), zinc dialkyldithiophosphate (ZDT), zinc2-ethylhexanoate (ZEH), zinc dinonyldithiocarbamate (ZNDNC), bismuthdimethyl dithiocarbamate (BIDD), nickel dibutyldithiocarbamate (NDBC),selenium diethyldithiocarbamate (SeEDC), seleniumdimethyldithiocarbamate (SeDMC), sodium diethyldithiocarbamate (SEDC),tellurium diethyldithiocarbamate (TeEDC), telluriumdiethyldithiocarbamate (TeDEC), sodium dimethyldithiocarbamate (SMDC),sodium dibutyldithiocarbamate (SBC) or sodiumcyclohexylethyldithiocarbarmate (SHEC).

A useful carbamate is preferably hexamethylene diaminocarbamate.

Preference is given to a vulcanizable composition comprising

-   (i) at least one optionally fully or partly hydrogenated nitrile    rubber containing epoxy groups and comprising repeat units derived    from at least one conjugated diene, at least one α,β-unsaturated    nitrile and optionally one or more further copolymerizable monomers,    but not from a nonconjugated cyclic polyene,-   (ii) at least one Lewis and/or Brønsted base as a crosslinker, and-   (iii) at least one crosslinking accelerator selected from the group    consisting of thiurams, xanthogenates, dithiocarbamates and    carbamates,    where the Lewis and/or Brønsted base (ii) must be different from the    defined group of crosslinking accelerators and also crosslinkers    other than those mentioned in (ii) are present in the vulcanizable    composition only in an amount of less than 2.5 parts by weight based    on 100 parts by weight of the optionally fully or partly    hydrogenated nitrile rubber (i) containing epoxy groups, and    crosslinking accelerators other than those mentioned in (iii) are    present only in an amount of less than 2.5 parts by weight based on    100 parts by weight of the optionally fully or partly hydrogenated    nitrile rubber (i) containing epoxy groups.

In a preferred embodiment, the inventive vulcanizable compositioncomprises

-   (i) at least one optionally fully or partly hydrogenated nitrile    rubber containing epoxy groups and comprising repeat units derived    from at least one conjugated diene, at least one α,β-unsaturated    nitrile and optionally one or more further copolymerizable monomers,    but not from a nonconjugated cyclic polyene,-   (ii) at least one Lewis base selected from the group consisting of    crown ethers, cryptands, tetraalkylammonium bromides, especially    tetra-n-butylammonium bromide, triphenylphosphine and bipyridine    and/or a Brønsted base selected from the group consisting of sodium    carbonate, potassium carbonate, calcium carbonate, lithium    carbonate, triethylamine, diisopropylamine, triethanolamine,    pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene,    1,4-diazabicyclo[2.2.2]octane, tetramethylethylenediamine,    pyrrolidine, pyrazole, piperidine, pyrrole, imidazole, urea, biuret,    dimethylurea, N,N′-dimethylpropyleneurea and sodium    dodecylbenzylsulphonate as a crosslinker,-   (iii) at least one crosslinking accelerator selected from the group    consisting of hexamethylene diaminocarbamate, tetramethylthiuram    disulphide (TMTD), tetramethylthiuram monosulphide (TMTM),    tetraethylthiuram disulphide (TETD), dipentamethylenethiuram    monosulphide (DPTM), dipentamethylenethiuram disulphide (DPTD),    dimethyldiphenylthiuram disulphide (MPTD), arylguanidinium    xanthogenates, zinc isopropylxanthogenate (ZIX), ethylenethiourea    (ETU), diphenylthiourea (DPTU), 1,3-di-o-tolylthiourea (DTTU),    diethylthiourea (DETU), zinc dimethyldithiocarbamate (ZDMC), zinc    diethyldithiocarbamate (ZDEC), zinc dibutyldithiocarbamate (ZDBC),    zinc ethylphenyldithiocarbamate (ZEPC), zinc dibenzyldithiocarbamate    (ZDBC), zinc pentamethylenedithiocarbamate (ZPD), sodium    diethyldithiocarbamate (SEDC), sodium dimethyldithiocarbamate    (SMDC), sodium dibutyldithiocarbamate (SBC) and sodium    cyclohexylethyldithiocarbamate (SHEC),    where crosslinkers other than those mentioned in (ii) are present in    the vulcanizable composition only in an amount of less than 2.5    parts by weight based on 100 parts by weight of the optionally fully    or partly hydrogenated nitrile rubber (i) containing epoxy groups,    and crosslinking accelerators other than those mentioned in (iii)    are present only in an amount of less than 2.5 parts by weight based    on 100 parts by weight of the optionally fully or partly    hydrogenated nitrile rubber (i) containing epoxy groups.

The amount of the crosslinker (ii) and of the crosslinking accelerator(iii) can be selected as a function of the concentration of the epoxygroups in the nitrile rubber.

The vulcanizable composition typically comprises

-   (i) at least one optionally fully or partly hydrogenated nitrile    rubber containing epoxy groups and comprising repeat units derived    from at least one conjugated diene, at least one α,β-unsaturated    nitrile and optionally one or more further copolymerizable monomers,    but not from a nonconjugated cyclic polyene, and-   (ii) 0.01 to 30 parts by weight, preferably 0.05 to 25 parts by    weight, more preferably 0.1 to 15 parts by weight and especially 0.2    to 10 parts by weight, based in each case on 100 parts by weight of    the nitrile rubber (i), of at least one Lewis and/or Brønsted base    as a crosslinker,-   (iii) 0.01 to 10 parts by weight, preferably 0.05 to 7.5 parts by    weight, more preferably 0.075 to 5 parts by weight and especially    0.1 to 3 parts by weight, based in each case on 100 parts by weight    of the nitrile rubber (i), of at least one crosslinking accelerator    selected from the group consisting of thiurams, xanthogenates,    thioureas, dithiocarbamates and carbamates, preferably selected from    the group consisting of thiurams, xanthogenates, dithiocarbamates    and carbamates,    where the Lewis and/or Brønsted base (ii) must be different from the    defined group of crosslinking accelerators (iii), and also    crosslinkers other than those mentioned in (ii) are present in the    vulcanizable composition only in an amount of less than 2.5 parts by    weight based on 100 parts by weight of the optionally fully or    partly hydrogenated nitrile rubber (i) containing epoxy groups, and    crosslinking accelerators other than those mentioned in (iii) are    present only in an amount of less than 2.5 parts by weight based on    100 parts by weight of the optionally fully or partly hydrogenated    nitrile rubber (i) containing epoxy groups.

According to the invention, the Lewis and/or Brønsted bases and thecrosslinking accelerator (iii) are added to the optionally fully orpartly hydrogenated nitrile rubber containing epoxy groups after theproduction thereof. The compounds are thus not those which are releasedor are already present in the course of production of the optionallyfully or partly hydrogenated nitrile rubber, or in the course ofcompounding thereof, but rather bases metered in separately or thecrosslinking accelerators defined. They are added to the nitrile rubberafter the production thereof. This avoids partial crosslinking orpartial gelation as early as in the course of production of the nitrilerubber.

Nitrile Rubber Containing Epoxy Groups:

The optionally fully or partly hydrogenated nitrile rubbers (i)containing epoxy groups used in the inventive vulcanizable compositionsmay be any suitable optionally fully or partly hydrogenated nitrilerubbers which have repeat units derived from at least one conjugateddiene, at least one α,β-unsaturated nitrile and optionally one or morefurther copolymerizable monomers, but not from a nonconjugated cyclicpolyene, and contain epoxy groups.

The epoxy groups can either be applied to the nitrile rubber bysubsequent grafting of compounds containing epoxy groups, or else can bederived from repeat units of a monomer containing epoxy groupsadditionally used in the production of the nitrile rubber.

Preference is given to using, in the inventive vulcanizable composition,optionally fully or partly hydrogenated nitrile rubbers containing epoxygroups and comprising repeat units of at least one nitrile, of at leastone conjugated diene, of at least one monomer containing epoxy groups,and optionally of one or more further copolymerizable monomers, but noneof any nonconjugated cyclic polyenes.

The nitrile rubbers containing epoxy groups are typically produced bypolymerizing the aforementioned monomers together to produce the nitrilerubber containing epoxy groups. This does not give a graft rubber whichhas been grafted with monomers containing epoxy groups, but rather arubber in which the monomer containing epoxy groups has beenincorporated into the polymer backbone in the form of repeat units inthe course of polymerization.

The monomers which contain epoxy groups and are used to produce thenitrile rubbers containing epoxy groups preferably have the generalformula (I)

in which

-   m is 0 or 1,-   X is O, O(CR₂)_(p), (CR₂)_(p)O, C(═O)O, C(═O)O(CR₂)_(p), C(═O)NR,    (CR₂)_(p), N(R), N(R)(CR₂)_(p), P(R), P(R)(CR₂)_(p), P(═O)(R),    P(═O)(R)(CR₂)_(p), S, S(CR₂)_(p), S(═O), S(═O)(CR₂)_(p),    S(═O)₂(CR₂)_(p) or S(═O)₂, where R in these radicals is the same or    different and may be as defined for R¹-R⁶,-   Y represents repeat units of one or more mono- or polyunsaturated    monomers, comprising conjugated or nonconjugated dienes, alkynes and    vinyl compounds, or a structural element which derives from polymers    comprising polyethers, especially polyalkylene glycol ethers and    polyalkylene oxides, polysiloxanes, polyols, polycarbonates,    polyurethanes, polyisocyanates, polysaccharides, polyesters and    polyamides,-   n and p are the same or different and are each in the range from 0    to 10 000,-   R, R¹, R², R³, R⁴, R⁵ and R⁶ are the same or different and are each    H, a linear or branched, saturated or mono- or polyunsaturated alkyl    radical, a saturated or mono- or polyunsaturated carbo- or    heterocyclyl radical, aryl, heteroaryl, arylalkyl, heteroarylalkyl,    alkoxy, aryloxy, heteroaryloxy, amino, amido, carbamoyl, alkylthio,    arylthio, sulphanyl, thiocarboxyl, sulphinyl, sulphono, sulphino,    sulpheno, sulphonic acids, sulphamoyl, hydroxyimino, alkoxycarbonyl,    F, Cl, Br, I, hydroxyl, phosphonato, phosphinato, silyl, silyloxy,    nitrile, borates, selenates, carbonyl, carboxyl, oxycarbonyl,    oxysulphonyl, oxo, thioxo, epoxy, cyanates, thiocyanates,    isocyanates, thioisocyanates or isocyanides.

Optionally, the definitions given for the R, R¹ to R⁶ radicals and therepeat units Y of the general formula (I) are each mono- orpolysubstituted.

The following radicals from the definitions for R, R¹ to R⁶ preferablyhave such mono- or polysubstitution: alkyl, carbocyclyl, heterocyclyl,aryl, heteroaryl, arylalkyl, heteroarylalkyl, alkoxy, aryloxy,alkylthio, arylthio, amino, amide, carbarnoyl, F, Cl, Br, I, hydroxyl,phosphonato, phosphinato, sulphanyl, thiocarboxyl, sulphinyl, sulphono,sulphino, sulpheno, sulphamoyl, silyl, silyloxy, carbonyl, carboxyl,oxycarbonyl, oxysulphonyl, oxo, thioxo, borates, selenates and epoxy.Useful substituents include—provided that chemically stable compoundsare the result all definitions that R can assume. Particularly suitablesubstituents are alkyl, carbocyclyl, aryl, halogen, preferably fluorine,chlorine, bromine or iodine, nitrile (CN) and carboxyl.

Particular preference is given to using a monomer which contains epoxygroups and is of the general formula (I) in which X, R, R¹ to R⁶ and mare each as defined for the general formula (I), p and n are the same ordifferent and are each in the range from 0 to 100.

Especially preferably, X, R, R¹ to R⁶ and m are each as defined abovefor the general formula (I) and p is in the range from 0 to 100 and n iszero. This monomer containing epoxy groups thus has the generalstructure (Ia)

in which

X, R, R¹ to R⁶, m and p are each as defined above for the generalformula (I).

Especially preferably, a monomer is used which contains epoxy groups andis of the general formula (I), in which X, R and R¹ to R⁶ are each asdefined above for the general formula (I), m is 1, p is 1 and n is zero.

Preferred examples of monomers containing epoxy groups are2-ethylglycidyl acrylate, 2-ethylglycidyl methacrylate,2-(n-propyl)glycidyl acrylate, 2-(n-propyl)glycidyl methacrylate,2-(n-butyl)glycidyl acrylate, 2-(n-butyl)glycidyl methacrylate, glycidylmethacrylate, glycidylmethyl methacrylate, glycidyl acrylate,(3′,4′-epoxyheptyl)-2-ethyl acrylate, (3′,4′-epoxyheptyl)-2-ethylmethacrylate, 6′,7′-epoxyheptyl acrylate, 6′,7′-epoxyheptylmethacrylate, allyl glycidyl ether, allyl 3,4-epoxyheptyl ether,6,7-epoxyheptyl allyl ether, vinyl glycidyl ether, vinyl 3,4-epoxyheptylether, 3,4-epoxyheptyl vinyl ether, 6,7-epoxyheptyl vinyl ether,o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether,p-vinylbenzyl glycidyl ether, 3-vinylcyclohexene oxide.

The monomer containing epoxy groups used is preferably a glycidyl(alkyl)acrylate. Particular preference is given to using glycidyl acrylate orglycidyl methacrylate.

In a preferred embodiment, the inventive vulcanizable compositioncomprises

-   (i) at least one optionally fully or partly hydrogenated nitrile    robber containing epoxy groups and comprising repeat units derived    from at least one conjugated diene, at least one α,β-unsaturated    nitrile, at least one monomer which contains epoxy groups and is    selected from the group consisting of 2-ethylglycidyl acrylate,    2-ethylglycidyl methacrylate, 2-(n-propyl)glycidyl acrylate,    2-(n-propyl)glycidyl methacrylate, 2-(n-butyl)glycidyl acrylate,    2-(n-butyl)glycidyl methacrylate, glycidyl methacrylate,    glycidylmethyl methacrylate, glycidyl acrylate,    (3′,4′-epoxyheptyl)-2-ethyl acrylate, (3′,4′-epoxyheptyl)-2-ethyl    methacrylate, 6′,7′-epoxyheptyl acrylate, 6′,7′-epoxyheptyl    methacrylate, allyl glycidyl ether, allyl 3,4-epoxyheptyl ether,    6,7-epoxyheptyl allyl ether, vinyl glycidyl ether, vinyl    3,4-epoxyheptyl ether, 3,4-epoxyheptyl vinyl ether, 6,7-epoxyheptyl    vinyl ether, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl    ether, p-vinylbenzyl glycidyl ether and 3-vinylcyclohexene oxide,    and optionally one or more further copolymerizable monomers, but not    from a nonconjugated cyclic polyene,-   (ii) at least one Lewis base selected from the group consisting of    crown ethers, cryptands, tetraalkylammonium bromides, especially    tetra-n-butylammonium bromide, triphenylphosphine and bipyridine    and/or at least one Brønsted base selected from the group consisting    of sodium carbonate, potassium carbonate, calcium carbonate, lithium    carbonate, triethylamine, diisopropylamine, triethanolamine,    pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene,    1,4-diazabicyclo[2.2.2]octane, tetramethylethylenediamine,    pyrrolidine, pyrazole, piperidine, pyrrole, imidazole, urea, biuret,    dimethylurea, N,N′-dimethylpropyleneurea and sodium    dodecylbenzylsulphonate as a crosslinker,-   (iii) at least one crosslinking accelerator selected from the group    consisting of hexamethylene diaminocarbamate, tetramethylthiuram    disulphide (TMTD), tetramethylthiuram monosulphide (TMTM),    tetraethylthiuram disulphide (TEM), dipentamethylenethiuram    monosulphide (DPTM), dipentamethylenethiuram disulphide (DPTD),    dimethyldiphenylthiuram disulphide (MPTD), arylguanidinium    xanthogenates, zinc isopropylxanthogenate (ZIX), ethylenethiourea    (ETU), diphenylthiourea (DPTU), 1,3-di-o-tolylthiourea (DTTU),    diethylthiourea (DETU), zinc dimethyldithiocarbamate (ZDMC), zinc    diethyldithiocarbamate (ZDEC), zinc dibutyldithiocarbamate (ZDBC),    zinc ethylphenyldithiocarbamate (ZEPC), zinc dibenzyldithiocarbamate    (ZDBC), zinc pentamethylenedithiocarbamate (ZPD), sodium    diethyldithiocarbamate (SEDC), sodium dimethyldithiocarbamate    (SMDC), sodium dibutyldithiocarbamate (SBC) and sodium    cyclohexylethyldithiocarbamate (SHEC),    where crosslinkers other than those mentioned in (ii) are present in    the vulcanizable composition only in an amount of less than 2.5    parts by weight, preferably only up to 1 part by weight and more    preferably only up to 0.75 part by weight, based on 100 parts by    weight of the optionally fully or partly hydrogenated nitrile    rubber (i) containing epoxy groups, and crosslinking accelerators    other than those mentioned in (iii) are present only in an amount of    less than 2.5 parts by weight, preferably only up to 1 part by    weight and more preferably only up to 0.75 part by weight, based on    100 parts by weight of the optionally fully or partly hydrogenated    nitrile rubber (i) containing epoxy groups.

In a particularly preferred embodiment, the inventive vulcanizablecomposition comprises

-   -   (i) at least one optionally fully or partly hydrogenated nitrile        rubber containing epoxy groups and comprising repeat units        derived from at least one conjugated diene, at least one        α,β-unsaturated nitrile, from glycidyl acrylate and/or glycidyl        methacrylate, and optionally one or more further copolymerizable        monomers, but not from a nonconjugated cyclic polyene,    -   (ii) at least one Lewis base selected from the group consisting        of crown ethers, cryptands, tetraalkylammonium bromides,        especially tetra-n-butylammonium bromide, and triphenylphosphine        or at least one Brønsted base selected from the group consisting        of sodium carbonate, potassium carbonate, lithium carbonate,        1,8-diazabicyclo[5.4.0]undec-7-ene,        1,4-diazabicyclo[2.2.2]octane, pyrrolidine, pyrazole, imidazole,        urea, biuret, dimethylurea, N,N′-dimethylpropyleneurea and        sodium dodecylbenzylsulphonate as a crosslinker,    -   (iii) at least one crosslinking accelerator selected from the        group consisting of hexamethylene diaminocarbamate,        tetramethylthiuram disulphide (TMTD), tetramethylthiuram        monosulphide (TMTM), tetraethylthiuram disulphide (TETD),        dipentamethylenethiuram disulphide (DPTD), zinc        isopropylxanthogenate (ZIX), ethylenethiourea (ETU),        1,3-di-o-tolylthiourea (DTTU), zinc dimethyldithiocarbamate        (ZDMC), zinc diethyldithiocarbamate (ZDEC), zinc        dibutyldithiocarbamate (ZDBC), zinc ethylphenyldithiocarbamate        (ZEPC), zinc pentamethylenedithiocarbamate (ZPD), sodium        diethyldithiocarbamate (SEDC) and sodium        cyclohexylethyldithiocarbamate (SHEC),        where crosslinkers other than those mentioned in (ii) are        present in the vulcanizable composition only in an amount of        less than 2.5 parts by weight, preferably only up to 1 part by        weight and more preferably only up to 0.75 part by weight, based        on 100 parts by weight of the optionally fully or partly        hydrogenated nitrile rubber (i) containing epoxy groups, and        crosslinking accelerators other than those mentioned in (iii)        are present only in an amount of less than 2.5 parts by weight,        preferably only up to 1 part by weight and more preferably only        up to 0.75 part by weight, based on 100 parts by weight of the        optionally fully or partly hydrogenated nitrile rubber (i)        containing epoxy groups.

Any conjugated diene may be present in the nitrile rubber containingepoxy groups. Preference is given to using (C₄-C₆) conjugated dienes.Particular preference is given to 1,2-butadiene, 1,3-butadiene,isoprene, 2,3-dimethylbutadiene, piperylene or mixtures thereof.Especially preferred are 1,3-butadiene and isoprene or mixtures thereof.Even more preferred is 1,3-butadiene.

The α,β-unsaturated nitrile used may be any known α,β-unsaturatednitrile, preference being given to (C₃-C₅)-α,β-unsaturated nitriles suchas acrylonitrile, methacrylonitrile, ethacrylonitrile or mixturesthereof. Particular preference is given to acrylonitrile.

The further copolymerizable monomers used—if desired—may be, forexample, aromatic vinyl monomers, preferably styrene, α-methylstyreneand vinylpyridine, fluorinated vinyl monomers, preferably fluoroethylvinyl ether, fluoropropyl vinyl ether, o-fluoromethylstyrene, vinylpentafluorobenzoate, difluoroethylene and tetrafluoroethylene, or elsecopolymerizable antiageing monomers, preferablyN-(4-anilinophenyl)acrylamide, N-(4-anilinophenyl)methacrylamide,N-(4-anilinophenyl)cinnamide, N-(4-anilinophenyl)crotonamide,N-phenyl-4-(3-vinylbenzyloxy)aniline andN-phenyl-4-(4-vinylbenzyloxy)aniline, and also nonconjugated dienes,such as 4-cyanocyclohexene and 4-vinylcyclohexene, or else alkynes, suchas 1- or 2-butyne.

In addition, the copolymerizable termonomers used may be monomerscontaining hydroxyl groups, preferably hydroxyalkyl (meth)acrylates. Itis also possible to use correspondingly substituted (meth)acrylamides.

Examples of suitable hydroxyalkyl acrylate monomers are 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl(meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate,3-phenoxy-2-hydroxypropyl (meth)acrylate, glyceryl mono(meth)acrylate,hydroxybutyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate,hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate,hydroxymethyl(meth)acrylamide, 2-hydroxypropyl (meth)acrylate,3-hydroxypropyl(meth)acrylamide, di(ethylene glycol) itaconate,di(propylene glycol) itaconate, bis(2-hydroxypropyl) itaconate,bis(2-hydroxyethyl) itaconate, bis(2-hydroxyethyl) fumarate,bis(2-hydroxyethyl) maleate and hydroxymethyl vinyl ketone.

Alternatively, further copolymerizable monomers used may becopolymerizable termonomers containing carboxyl groups, for exampleα,β-unsaturated monocarboxylic acids, esters thereof, α,β-unsaturateddicarboxylic acids, mono- or diesters thereof or the correspondinganhydrides or amides thereof.

The α,β-unsaturated monocarboxylic acids used may preferably be acrylicacid and methacrylic acid.

It is also possible to use esters of the α,β-unsaturated monocarboxylicacids, preferably the alkyl esters and alkoxyalkyl esters thereof.Preference is given to the alkyl esters, especially C₁-C₁₈ alkyl esters,of the α,β-unsaturated monocarboxylic acids, particular preference toalkyl esters, especially C₁-C₁₈ alkyl esters of acrylic acid or ofmethacrylic acid, especially methyl acrylate, ethyl acrylate, propylacrylate, n-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate,n-dodecyl acrylate, methyl methacrylate, ethyl methacrylate, butylmethacrylate and 2-ethylhexyl methacrylate. Preference is also given toalkoxyalkyl esters of the α,β-unsaturated monocarboxylic acids,particular preference to alkoxyalkyl esters of acrylic acid or ofmethacrylic acid, especially C₂-C₁₂-alkoxyalkyl esters of acrylic acidor of methacrylic acid, even more preferably methoxymethyl acrylate,methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate and methoxyethyl(meth)acrylate. It is also possible to use mixtures of alkyl esters, forexample those mentioned above, with alkoxyalkyl esters, for example inthe form of those mentioned above. It is also possible to use cyanoalkylacrylates and cyanoalkyl methacrylates in which the number of carbonatoms in the cyanoalkyl group is 2-12, preferably α-cyanoethyl acrylate,β-cyanoethyl acrylate and cyanobutyl methacrylate. It is also possibleto use hydroxyalkyl acrylates and hydroxyalkyl methacrylates in whichthe number of carbon atoms of the hydroxyalkyl groups is 1-12,preferably 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and3-hydroxypropyl acrylate; it is also possible to use acrylates ormethacrylates containing fluorine-substituted benzyl groups, preferablyfluorobenzyl acrylate and fluorobenzyl methacrylate. It is also possibleto use acrylates and methacrylates containing fluoroalkyl groups,preferably trifluoroethyl acrylate and tetrafluoropropyl methacrylate.It is also possible to use α,β-unsaturated carboxylic esters containingamino groups, such as dimethylaminomethyl acrylate and diethylaminoethylacrylate.

Further copolymerizable monomers used may additionally beα,β-unsaturated dicarboxylic acids, preferably maleic acid, fumaricacid, crotonic acid, itaconic acid, citraconic acid and mesaconic acid.

It is additionally possible to use α,β-unsaturated dicarboxylicanhydrides, preferably maleic anhydride, itaconic anhydride, citraconicanhydride and mesaconic anhydride.

It is additionally possible to use mono- or diesters of α,β-unsaturateddicarboxylic acids.

These α,β-unsaturated dicarboxylic mono- or diesters may, for example,be alkyl, preferably C₁-C₁₀-alkyl, especially ethyl, n-propyl,isopropyl, n-butyl, tert-butyl, n-pentyl or n-hexyl, alkoxyalkyl,preferably C₂-C₁₂-alkoxyalkyl, more preferably C₃-C₈-alkoxyalkyl,hydroxyalkyl, preferably C₁-C₁₂-hydroxyalkyl, more preferablyC₂-C₈-hydroxyalkyl, cycloalkyl, preferably C₅-C₁₂-cycloalkyl, morepreferably C₆-C₁₂-cycloalkyl, alkylcycloalkyl, preferablyC₆-C₁₂-alkylcycloalkyl, more preferably C₇-C₁₀-alkylcycloalkyl, aryl,preferably C₆-C₁₄-aryl mono- or diesters, where the diesters in eachcase may also be mixed esters.

Particularly preferred alkyl esters of α,β-unsaturated monocarboxylicacids are methyl (meth)acrylate, ethyl (meth)acrylate, propyl(meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, hexyl(meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate,2-propylheptyl acrylate and lauryl (meth)acrylate. In particular,n-butyl acrylate is used.

Particularly preferred alkoxyalkyl esters of the α,β-unsaturatedmonocarboxylic acids are methoxyethyl (meth)acrylate, ethoxyethyl(meth)acrylate and methoxyethyl (meth)acrylate. In particular,methoxyethyl acrylate is used.

Other esters of the α,β-unsaturated monocarboxylic acids used areadditionally, for example, polyethylene glycol (meth)acrylate,polypropylene glycol (meth)acrylate, N-(2-hydroxyethyl)acrylamide,N-(2-hydroxymethyl)acrylamide and urethane (meth)acrylate.

Examples of α,β-unsaturated dicarboxylic monoesters include

-   -   monoalkyl maleates, preferably monomethyl maleate, monoethyl        maleate, monopropyl maleate and mono-n-butyl maleate;    -   monocycloalkyl maleates, preferably monocyclopentyl maleate,        monocyclohexyl maleate and monocycloheptyl maleate;    -   monoalkylcycloalkyl maleates, preferably monomethylcyclopentyl        maleate and monoethylcyclohexyl maleate;    -   monoaryl maleates, preferably monophenyl maleate;    -   monobenzyl maleates, preferably monobenzyl maleate;    -   monoalkyl fumarates, preferably monomethyl fumarate, monoethyl        fumarate, monopropyl fumarate and mono-n-butyl fumarate;    -   monocycloalkyl fumarates, preferably monocyclopentyl fumarate,        monocyclohexyl fumarate and monocycloheptyl fumarate;    -   monoalkylcycloalkyl fumarates, preferably monomethylcyclopentyl        fumarate and monoethylcyclohexyl fumarate;    -   monoaryl fumarates, preferably monophenyl fumarate;    -   monobenzyl fumarates, preferably monobenzyl fumarate;    -   monoalkyl citraconates, preferably monomethyl citraconate,        monoethyl citraconate, monopropyl citraconate and mono-n-butyl        citraconate;    -   monocycloalkyl citraconates, preferably monocyclopentyl        citraconate, monocyclohexyl citraconate and monocycloheptyl        citraconate;    -   monoalkylcycloalkyl citraconates, preferably        monomethylcyclopentyl citraconate and monoethylcyclohexyl        citraconate;    -   monoaryl citraconates, preferably monophenyl citraconate;    -   monobenzyl citraconates, preferably monobenzyl citraconate;    -   monoalkyl itaconates, preferably monomethyl itaconate, monoethyl        itaconate, monopropyl itaconate and mono-n-butyl itaconate;    -   monocycloalkyl itaconates, preferably monocyclopentyl itaconate,        monocyclohexyl itaconate and monocycloheptyl itaconate;    -   monoalkylcycloalkyl itaconates, preferably monomethylcyclopentyl        itaconate and monoethylcyclohexyl itaconate;    -   monoaryl itaconates, preferably monophenyl itaconate;    -   monobenzyl itaconates, preferably monobenzyl itaconate;    -   monoalkyl mesaconates, preferably monoethyl mesaconate.

The α,β-unsaturated dicarboxylic diesters used may be the analogousdiesters based on the aforementioned monoester groups, where the estergroups may also be chemically different groups.

Useful further copolymerizable monomers are additionally free-radicallypolymerizable compounds containing at least two olefinic double bondsper molecule. Examples of polyunsaturated compounds are acrylates,methacrylates or itaconates of polyols, for example ethylene glycoldiacrylate, diethylene glycol dimethacrylate, triethylene glycoldiacrylate, butanediol 1,4-diacrylate, propane-1,2-diol diacrylate,butane-1,3-diol dimethacrylate, neopentyl glycol diacrylate,trimethylolpropane di(meth)acrylate, trimethylolethane di(meth)acrylate,glyceryl di- and triacrylate, pentaerythrityl di-, tri- andtetraacrylate or -methacrylate, dipentaerythrityl tetra-, penta- andhexaacrylate or -methacrylate or -itaconate, sorbityl tetraacrylate,sorbityl hexamethacrylate, diacrylates or dimethacrylates of1,4-cyclohexanediol, 1,4-dimethylolcyclohexane,2,2-bis(4-hydroxyphenyl)propane, of polyethylene glycols or ofoligoesters or oligourethanes with terminal hydroxyl groups. Thepolyunsaturated monomers used may also be acrylamides, for examplemethylenebisacrylamide, hexamethylene-1,6-bisacrylamide,diethylenetriaminetrismethacrylamide, bis(methacrylamidopropoxy)ethaneor 2-acrylamidoethyl acrylate. Examples of polyunsaturated vinyl andallyl compounds are divinylbenzene, ethylene glycol divinyl ether,diallyl phthalate, allyl methacrylate, diallyl maleate, triallylisocyanurate or triallyl phosphate.

In a preferred embodiment, the inventive vulcanizable compositioncomprises

-   (i) at least one optionally fully or partly hydrogenated nitrile    rubber containing epoxy groups and comprising repeat units derived    from a) acrylonitrile, b) 1,3-butadiene, c) at least one monomer    which contains epoxy groups and is selected from the group    consisting of 2-ethylglycidyl acrylate, 2-ethylglycidyl    methacrylate, 2-(n-propyl)glycidyl acrylate, 2-(n-propyl)glycidyl    methacrylate, 2-(n-butyl)glycidyl acrylate, 2-(n-butyl)glycidyl    methacrylate, glycidyl methacrylate, glycidylmethyl methacrylate,    glycidyl acrylate, (3′,4′-epoxyheptyl)-2-ethyl acrylate,    (3′,4′-epoxyheptyl)-2-ethyl methacrylate, 6′,7′-epoxyheptyl    acrylate, 6′,7′-epoxyheptyl methacrylate, allyl glycidyl ether,    allyl 3,4-epoxyheptyl ether, 6,7-epoxyheptyl allyl ether, vinyl    glycidyl ether, vinyl 3,4-epoxyheptyl ether, 3,4-epoxyheptyl vinyl    ether, 6,7-epoxyheptyl vinyl ether, o-vinylbenzyl glycidyl ether,    m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether and    3-vinylcyclohexene oxide, and d) optionally one or more further    copolymerizable monomers, but not from a nonconjugated cyclic    polyene,-   (ii) at least one Lewis base selected from the group consisting of    crown ethers, cryptands, tetraalkylammonium bromides, especially    tetra-n-butylammonium bromide, and triphenylphosphine and/or a    Brønsted base selected from the group consisting of sodium    carbonate, potassium carbonate, lithium carbonate,    1,8-diazabicyclo[5.4.0]undec-7-ene, 1,4-diazabicyclo[2.2.2]octane,    pyrrolidine, pyrazole, imidazole, urea, biuret, dimethylurea,    N,N′-dimethylpropyleneurea and sodium dodecylbenzylsulphonate as a    crosslinker and-   (iii) at least one crosslinking accelerator selected from the group    consisting of hexamethylene diaminocarbamate, tetramethylthiuram    disulphide (TMTD), tetramethylthiuram monosulphide (TMTM),    tetraethylthiuram disulphide (TETD), dipentamethylenethiuram    disulphide (DPTD), zinc isopropylxanthogenate (ZIX),    ethylenethiourea (ETU), 1,3-di-o-tolylthiourea (DTTU), zinc    dimethyldithiocarbamate (ZDMC), zinc diethyldithiocarbamate (ZDEC),    zinc dibutyldithiocarbamate (ZDBC), zinc ethylphenyldithiocarbamate    (ZEPC), zinc pentamethylenedithiocarbamate (ZPD), sodium    diethyldithiocarbamate (SEDC) and sodium    cyclohexylethyldithiocarbamate (SHEC),    where crosslinkers other than those mentioned in (ii) are present in    the vulcanizable composition only in an amount less than 2.5 parts    by weight, preferably only up to 1 part by weight and more    preferably only up to 0.75 part by weight, based on 100 parts by    weight of the optionally fully or partly hydrogenated nitrile    rubber (i) containing epoxy groups, and crosslinking accelerators    other than those mentioned in (iii) only in an amount of less than    2.5 parts by weight, preferably only up to 1 part by weight and more    preferably only up to 0.75 part by weight, based on 100 parts by    weight of the optionally fully or partly hydrogenated nitrile    rubber (i) containing epoxy groups.

In a preferred embodiment, the inventive vulcanizable compositioncomprises

-   (i) at least one optionally fully or partly hydrogenated nitrile    rubber containing epoxy groups and comprising repeat units derived    from a) acrylonitrile, b) 1,3-butadiene, c) glycidyl acrylate and/or    glycidyl methacrylate, and d) optionally one or more further    copolymerizable monomers, but not from a nonconjugated cyclic    polyene,-   (ii) at least one Lewis base selected from the group consisting of    crown ethers, cryptands, tetraalkylammonium bromides, especially    tetra-n-butylammonium bromide, and triphenylphosphine and/or a    Brønsted base selected from the group consisting of sodium    carbonate, potassium carbonate, lithium carbonate,    1,8-diazabicyclo[5.4.0]undec-7-ene, 1,4-azabicyclo[2.2.2]octane,    pyrrolidine, pyrazole, imidazole, urea, biuret, dimethylurea,    N,N′-dimethylpropyleneurea and sodium dodecylbenzylsulphonate as a    crosslinker,-   (iii) at least one crosslinking accelerator selected from the group    consisting of hexamethylene diaminocarbamate, tetramethylthiuram    disulphide (TMTD), tetramethylthiuram monosulphide (TMTM),    tetraethylthiuram disulphide (TETD), dipentamethylenethiuram    disulphide (DPTD), zinc isopropylxanthogenate (ZIX),    ethylenethiourea (ETU), 1,3-di-o-tolylthiourea (DTTU), zinc    dimethyldithiocarbamate (ZDMC), zinc diethyldithiocarbamate (ZDEC),    zinc dibutyldithiocarbamate (ZDBC), zinc ethylphenyldithiocarbamate    (ZEPC), zinc pentamethylenedithiocarbamate (ZPD), sodium    diethyldithiocarbamate (SEDC) and sodium    cyclohexylethyldithiocarbamate (SHEC),    where crosslinkers other than those mentioned in (ii) are present in    the vulcanizable composition only in an amount less than 2.5 parts    by weight, preferably only up to 1 part by weight and more    preferably only up to 0.75 part by weight, based on 100 parts by    weight of the optionally fully or partly hydrogenated nitrile    rubber (i) containing epoxy groups, and crosslinking accelerators    other than those mentioned in (iii) are present only in an amount of    less than 2.5 parts by weight, preferably only up to 1 part by    weight and more preferably only up to 0.75 part by weight, based on    100 parts by weight of the optionally fully or partly hydrogenated    nitride rubber (i) containing epoxy groups.

Ratios of the Monomers:

The proportions of the respective monomers in the optionally fully orpartly hydrogenated nitrile rubbers which contain epoxy groups and areto be used in accordance with the invention can vary within wide ranges.

The proportion of, or of the sum of, the conjugated diene(s) istypically in the range from 39.75 to 90% by weight, preferably in therange from 44 to 88% by weight, more preferably 45.75 to 87% andespecially 47.5 to 85% by weight, based on the overall nitrile rubber.

The proportion of, or of the sum of, the α,β-unsaturated nitrile(s) istypically 5 to 60% by weight, preferably 10 to 55% by weight, morepreferably 13 to 53% by weight and especially 15 to 51% by weight, basedon overall nitrile rubber.

The proportion of monomers containing epoxy groups is preferably 0.25 to35% by weight, more preferably 1 to 30% by weight, more preferably 1.25to 25% by weight and especially 1.5 to 18% by weight, based on overallnitrile rubber.

The proportions of all monomers must in each case add up to 100% byweight.

The amount of monomer containing epoxy groups in the nitrile rubber (i),the amount of the crosslinker (ii) and of the crosslinking accelerator(iii) and the ratio of epoxy groups to crosslinker (ii) and crosslinkingaccelerator (iii) is set according to the desired degree ofcrosslinking. By setting the ratio of epoxy groups to the amount ofcrosslinker (ii) and crosslinking accelerator (iii), it is possible toadjust the elongation at break and tensile strength to the particularrequirements.

The optional further copolymerizable monomers may, according to theirnature, be present in amounts of 0 to 50% by weight, based on theoverall nitrile rubber (i). In this case, corresponding proportions ofthe conjugated diene(s) and/or of the α,β-unsaturated nitrile(s) and/orof the monomer containing epoxy groups may be replaced by theproportions of the additional monomers, where the proportions of allmonomers must again in each case add up to 100% by weight.

The preparation of such optionally fully or partly hydrogenated nitrilerubbers containing epoxy groups is sufficiently well-known to thoseskilled in the art. The nitrile rubber containing epoxy groups istypically prepared by what is called an emulsion polymerization. This isconducted in the presence of emulsifiers, which are typicallywater-soluble salts of anionic emulsifiers or else unchargedemulsifiers. In addition, polymerization is frequently effected in thepresence of what are called molecular weight regulators, which aregenerally alkyl thiols containing 12-16 carbon atoms, preferablytert-dodecyl mercaptans (t-DDM). Such alkyl thiols or (isomer) mixturesof alkyl thiols are either commercially available or else are preparableby processes sufficiently well-described in the literature for theperson skilled in the art.

To conduct the polymerization, all or individual components of theinitiator system are metered in at the start of the polymerizationand/or during the polymerization. Addition of all and individualcomponents in portions during the polymerization is preferred.Sequential addition can be used to control the reaction rate. To achievehomogeneous running of the polymerization, only a portion of theinitiator system is used for the start of the polymerization and therest is metered in during the polymerization. Typically, thepolymerization is commenced with 10 to 80% by weight, preferably 30-50%by weight, of the total amount of initiator. It is also possible tosubsequently meter in individual constituents of the initiator system.If the intention is to prepare chemically homogeneous products, themonomers are metered in. Acrylonitrile and butadiene in particular aremetered in subsequently if the composition is outside the azeotropicbutadiene/acrylonitrile ratio. Preference is given to subsequent meteredaddition in the case of NBR types with acrylonitrile contents of 10 to34% by weight, and in the case of the types with 40 to 50% by weight ofacrylonitrile (W. Hofmann, Rubber Chem. Technol. 36 (1963). Thepolymerization time is in the range from 5 h to 15 h and dependsparticularly on the acrylonitrile content of the monomer mixture and onthe polymerization temperature. The latter is in the range from 0 to 30°C., preferably in the range from 5 to 25° C. On attainment ofconversions in the range from 50 to 90%, preferably in the range from 60to 85%, the polymerization is ended, typically by adding a commonlyknown stopper. The amount of water used in the emulsion polymerizationis in the range from 100 to 900 parts by weight, preferably in the rangefrom 120 to 500 parts by weight and more preferably in the range from150 to 400 parts by weight of water, based on 100 parts by weight of themonomer mixture. The polymerization can be performed either batchwise orelse continuously in a stirred tank cascade. To remove unconvertedmonomers and volatile constituents, the “stopped” latex is subjected toa steam distillation. In this case, temperatures in the range from 70°C. to 150° C. are employed, the pressure being reduced in the case oftemperatures of <100° C. Before the volatile constituents are removed,the latex can be post-stabilized with emulsifier. For this purpose, theaforementioned emulsifiers are appropriately used in amounts of 0.1 to2.5% by weight, preferably 0.5 to 2.0% by weight, based on 100 parts byweight of nitrile rubber.

Metathesis and Hydrogenation:

It is also possible that the preparation of the nitrile rubber (a)containing epoxy groups is followed by a metathesis reaction to reducethe molecular weight of the nitrile rubber or (b) a metathesis reactionand a subsequent hydrogenation or (c) only a hydrogenation. Thesemetathesis or hydrogenation reactions are sufficiently well-known tothose skilled in the art and are described in the literature. Metathesisis known, for example, from WO-A-02/100941 and WO-A-02/100905 and can beused to reduce the molecular weight.

The hydrogenation can be performed using homogeneous or heterogeneoushydrogenation catalysts. The catalysts used are based typically onrhodium, ruthenium or titanium, but it is also possible to use platinum,iridium, palladium, rhenium, ruthenium, osmium, cobalt or copper, eitheras the metal or else preferably in the form of metal compounds (see, forexample, U.S. Pat. No. 3,700,637, DE-A-25 39 132, EP-A-0 134 023,DE-A-35 41 689, DE-A-35 40 918, EP-A-0 298 386, DE-A-35 29 252, DE-A-3433 392, U.S. Pat. No. 4,464,515 and U.S. Pat. No. 4,503,196).

Suitable catalysts and solvents for a hydrogenation in homogeneous phaseare described hereinafter and are also known from DE-A-25 39 132 andEP-A-0 471 250. The selective hydrogenation can be achieved, forexample, in the presence of a rhodium or ruthenium catalyst. It ispossible to use, for example, a catalyst of the general formula(R¹ _(m)B)_(l)MX_(n)in which M is ruthenium or rhodium. R¹ is the same or different and is aC₁-C₈ alkyl group, a C₄-C₈ cycloalkyl group, a C₆-C₁₅ aryl group or aC₇-C₁₅ aralkyl group. B is phosphorus, arsenic, sulphur or a sulphoxidegroup S═O, X is hydrogen or an anion, preferably halogen and morepreferably chlorine or bromine, l is 2, 3 or 4, m is 2 or 3 and n is 1,2 or 3, preferably 1 or 3. Preferred catalysts aretris(triphenylphosphine)rhodium(I) chloride,tris(triphenylphosphine)rhodium(III) chloride andtris(dimethylsulphoxide)rhodium(I) chloride, and alsotetrakis(triphenylphosphine)rhodium hydride of the formula (C₆H₅)₃P)₄RhHand the corresponding compounds in which the triphenylphosphine has beenreplaced fully or partly by tricyclohexylphosphine. The catalyst can beused in small amounts. An amount in the range of 0.01-1% by weight,preferably in the range of 0.03-0.5% by weight and more preferably inthe range of 0.1-0.3% by weight, based on the weight of the polymer, issuitable.

It is typically advisable to use the catalyst together with a cocatalystwhich is a ligand of the formula R¹ _(m)B where R¹, m and B are each asdefined above for the catalyst. Preferably, in is 3, B is phosphorus andthe R¹ radicals may be the same or different. The cocatalysts preferablyhave trialkyl, tricycloalkyl, triaryl, triaralkyl, diaryl monoalkyl,diaryl monocycloalkyl, dialkyl monoaryl, dialkyl monocycloalkyl,dicycloalkyl monoaryl or dicycloalkyl monoaryl radicals.

Examples of cocatalysts can be found, for example, in U.S. Pat. No.4,631,315. A preferred cocatalyst is triphenylphosphine. The cocatalystis used preferably in amounts within a range of 0.3-5% by weight,preferably in the range of 0.5-4% by weight, based on the weight of thenitrile rubber to be hydrogenated. Preferably, in addition, the weightratio of the rhodium catalyst to the cocatalyst is in the range from 1:3to 1:55, more preferably in the range from 1:5 to 1:45, based on 100parts by weight of the nitrile rubber to be hydrogenated; preferably 0.1to 33 parts by weight of the cocatalyst, more preferably 0.5 to 20 andeven more preferably 1 to 5 parts by weight, especially more than 2 butless than 5 parts by weight, of cocatalyst based on 100 parts by weightof the nitrile rubber to be hydrogenated, are used.

The practical conduct of the hydrogenation is known to those skilled inthe art from U.S. Pat. No. 6,683,136. It is effected typically bycontacting the nitrile rubber to be hydrogenated with hydrogen in asolvent such as toluene or monochlorobenzene at a temperature in therange from 100 to 150° C. and a pressure in the range from 50 to 150 barfor 2 to 10 h.

Hydrogenation is understood in the context of this invention to mean aconversion of the double bonds present in the starting nitrile rubber toan extent of at least 50%, preferably 70-100%, more preferably 80-100%.The determination of the degree of hydrogenation is well-known to thoseskilled in the art and can be effected, for example, by Raman or IRspectroscopy (see, for example, EP-A-0 897 933 for the determination byRaman spectroscopy or U.S. Pat. No. 6,522,408 for the determination viaIR spectroscopy).

In the case of use of heterogeneous catalysts, these are typicallysupported catalysts based on palladium, which are supported, forexample, on charcoal, silica, calcium carbonate or barium sulphate.

This affords fully or partly hydrogenated nitrile rubbers containingepoxy groups. These have repeat units derived from at least oneconjugated diene, at least one α,β-unsaturated nitrile and optionallyone or more further copolymerizable monomers, but not from anonconjugated cyclic polyene.

These optionally fully or partly hydrogenated nitrile rubbers containingepoxy groups typically have Mooney viscosities (ML (1+4@100° C.)) in therange from 10 to 160 and preferably from 15 to 150 Mooney units, morepreferably from 20 to 150 Mooney units and especially 25 to 145 Mooneyunits. The values of the Mooney viscosity (ML 1+4@100° C.) aredetermined by means of a shearing disc 2.5 viscometer to DIN 53523/3 orASTM 1) 1646 at 100° C.

The optionally fully or partly hydrogenated nitrile rubbers containingepoxy groups typically additionally have a polydispersityPDI=M_(w)/M_(n), where M_(w) is the weight-average and M_(n) thenumber-average molecular weight, in the range from 1.0 to 6.0 andpreferably in the range from 1.5 to 5.0.

The glass transition temperatures of the optionally fully or partlyhydrogenated nitrile rubbers containing epoxy groups are in the rangefrom −80° C. to +20° C., preferably in the range from −70° C. to +10° C.and more preferably in the range from −60° C. to 0° C.

A preferred embodiment of the invention concerns vulcanizablecompositions which additionally comprise (iv) at least one filler. Thisfiller comprises exclusively compounds not already encompassed by theinventive crosslinkers (ii) or crosslinking accelerators (iii). It ispossible to use, for example, carbon black, silica, carbon nanotubes,Teflon (the latter preferably in powder form) or silicates.

In further embodiments, the inventive vulcanizable compositions may alsocomprise one or more additives familiar to the person skilled in the artof rubber. These too are exclusively compounds not covered by thedefinition of the inventive crosslinkers (ii) or crosslinkingaccelerators (iii). These additives include filler activators, ageingstabilizers, reversion stabilizers, light stabilizers, ozonestabilizers, processing aids, plasticizers, mineral oils, tackifiers,blowing agents, dyes, pigments, waxes, resins, extenders, vulcanizationretardants, and further or other additives known in the rubber industry(Ullmann's Encyclopedia of Industrial Chemistry, VCH VerlagsgesellschaftmbH, D-69451 Weinheim, 1993, vol A 23 “Chemicals and Additives”, p.366-417).

Useful filler activators include, for example, organic silanes,preferably vinyltrimethyloxysilane, vinyldimethoxymethyl silane, vinyltriethoxysilane, vinyl tris(2-methoxyethoxy)silane,N-cyclohexyl-3-aminopropyltrimethoxysilane,3-aminopropyltrimethoxysilane, methyltrimethoxysilane,methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane,trimethylethoxysilane, isooctyltrimethoxysilane,isooctyltriethoxysilane, hexadecyltrimethoxysilane or(oetadecyl)methyldimethoxysilane. Further filler activators are, forexample, interface-active substances such as triethanolamine,trimethylolpropane, hexanetriol, and polyethylene glycols with molecularweights of 74 to 10 000 g/mol. The amount of filler activators istypically 0 to 10 parts by weight, based on 100 parts by weight of theoptionally fully or partly hydrogenated nitrile rubber containingepoxide groups.

The ageing stabilizers which may be added to the vulcanizablecompositions may be any of those known to those skilled in the art,which are used typically in amounts of 0 to 5 parts by weight,preferably 0.5 to 3 parts by weight, based on 100 parts by weight of theoptionally hydrogenated nitrile rubber containing epoxide groups.

Useful mould release agents include, for example, saturated or partlyunsaturated acids of fats and oils, and derivatives thereof (fatty acidesters, fatty acid salts, fatty alcohols, fatty acid amides). Inaddition, it is possible to use products applicable to the mouldsurface, for example products based on low molecular weight siliconecompounds, products based on fluoropolymers and products based on phenolresins. The mould release agents are used in amounts of 0 to 10 parts byweight, preferably 0.5 to 5 parts by weight, based on 100 parts byweight of the optionally hydrogenated nitrile rubber containing epoxidegroups.

Another possibility is reinforcement with strengthening agents (fibres)made of glass, according to the teaching of U.S. Pat. No. 4,826,721, andanother is reinforcement by cords, woven fabrics, fibres made ofaliphatic and aromatic polyamides (Nylon®, Aramid®), polyesters andnatural fibre products.

The invention further provides the process for producing thevulcanizable compositions by mixing at least one fully or partlyhydrogenated nitrile rubber (i) containing epoxy groups with at leastone Lewis and/or Brønsted acid (ii) and at least one crosslinkingaccelerator (iii). This mixing operation can be effected in all mixingapparatuses familiar to those skilled in the art. Typically, the atleast one crosslinker (ii) and the at least one crosslinking accelerator(iii) are metered into the nitrile rubber (i). When one or more fillersand one or more further rubber additives are used, they can also bemixed in in any desired sequence.

The invention further provides a process for producing vulcanizatesbased on an optionally fully or partly hydrogenated nitrile rubbercontaining epoxy groups, characterized in that the aforementionedvulcanizable composition is crosslinked with increasing temperature. Thecrosslinking can be effected at temperatures in the range frompreferably 20 to 250° C., more preferably 50 to 230° C. The duration ofthe crosslinking reaction is in the range from one (1) minute to severaldays.

The invention also provides the vulcanizates thus obtainable. Thesevulcanizates contain crosslinked, optionally fully or partlyhydrogenated nitrile rubbers containing epoxy groups. They exhibit verygood values in the compression set test at room temperature, 100° C. and150° C., and additionally high tensile strength coupled with goodelongations at break.

EXAMPLES

The nitrogen content for determination of the acrylonitrile content(“ACN content”) in the inventive optionally fully or partly hydrogenatednitrile rubbers containing epoxy groups is determined to DIN 53 625according to Kjeldahl. Due to the content of polar comonomers, theoptionally hydrogenated nitrile rubbers containing epoxy groups aretypically >85% by weight soluble in methyl ethyl ketone at 20° C.

The glass transition temperature and what are called the onset andoffset points thereof are determined by means of Differential ScanningCalorimetry (DSC) to ASTM E 1356-03 or to DIN 11357-2.

The microstructure and the termonomer content of the individual polymerswere determined by means of 1H NMR (instrument: Bruker DPX400 withXWIN-NMR 3.1 software, measurement frequency 400 MHz, solvent CDCl3).

The values of the Mooney viscosity (ML 1+4@100° C.) are determined ineach case by means of a shearing disc viscometer to DIN 53523/3 or ASTMD 1646 at 100° C. The MSR (Mooney Stress Relaxation) is determined ineach case by means of a shearing disc viscometer to ISO 289-4:2003(E) at100° C.

The vulcanization profile in the MDR and the analytical data thereofwere measured on a Monsanto MDR 2000 rheometer to ASTM D5289-95.

The compression set (“CS”) at the temperature specified was measured toDIN 53517.

The Shore A hardness was measured to ASTM-D2240-81.

The tensile tests to determine stress as a function of deformation wereconducted to DIN 53504 or ASTM D412-80.

The abbreviations given in the tables below have the following meanings:

-   “RT” room temperature (23±2° C.)-   “TS” tensile strength, measured at RT-   “EB” elongation at break, measured at RT-   “M50” modulus at 50% elongation, measured at RT-   “M100” modulus at 100% elongation, measured at RT-   “M300” modulus at 300% elongation, measured at RT-   “S min” is the minimum torque of the crosslinking isotherm-   “S max” is the maximum torque of the crosslinking isotherm-   “delta S” is “S max−S min”-   “t₁₀” is the time when 10% of S max is attained-   “t₅₀” is the time when 50% of S max is attained-   “t₉₀” is the time when 90% of S max is attained-   “t₉₅” is the time when 95% of S max is attained-   “TS2” is the time by which the Mooney viscosity has increased by two    units compared with the starting point

The following substances used in the examples:

The following chemicals were purchased as commercial products from thecompanies specified in each case, or originate from production plants ofthe companies specified.

Crosslinker (ii):

-   Lupragen® N 700 1,8-diazabicyclo-5,4,0-undecene-7 (commercial    product from BASF AG)

Crosslinking Accelerator (iii):

-   Vulkacit® P Extra N zinc ethylphenyldithiocarbamate (Lauxess    Deutschland GmbH)-   VULCOFAC® HDC hexamethylene diaminocarbamate (Safic-Alcan    Deutschland GmbH)-   RHENOCURE® SDT/S70% phosphoryl polysulfide bound to 30%    high-activity silica (Lanxess Deutschland GmbH)

Other Substances Used in the Polymerization or in the VulcanizableComposition:

-   Corax® N550/30 carbon black (commercial product from Evonik Degussa)-   Diplast® TM 8-10/ST trioctyl mellitate (commercial product from    Lonza SpA)-   Luvomaxx® CDPA p-dicumyldiphenylamine (commercial product from    Lehmann & Voss)-   Wingstay® 29/Naugawhite mixture: mixture of 25 g of Sorbilene Mix    (mixture of Sorbitan esters and ethoxylated sorbitan esters) from    Lamberti, 38 g of Nauga-white (2,2′-methylenebis(6-nonyl-p-cresol))    from Chemtura, 125 g of Wingstay® 29 (styrenized diphenylamine) from    Eliokem and 63 g of water-   “Fe(II)SO₄ premix solution” contains 0.986 g of Fe(II)SO₄*7 H₂O and    2.0 g of Rongalit®C in 400 g of water-   Rongalit® C sodium salt of a sulphinic acid derivative (commercial    product from BASF SE)-   t-DDM tertiary dodecyl mercaptan (Lanxess Deutschland GmbH)-   Texapon® K-12 sodium laurylsulphate (commercial product from Cognis    Deutschland GmbH & Co. KG)-   Trigonox® NT 50 p-menthane hydroperoxide (commercial product from    Akzo-Degussa)

I Production of Nitrile Rubber A

Nitrile rubber A used in the example series which follow was producedaccording to the base formulation specified in Table 1, with allfeedstocks stated in parts by weight based on 100 parts by weight of themonomer mixture. Table 1 also specifies the respective polymerizationconditions.

TABLE 1 Production of nitrile rubber A Nitrile rubber A butadiene 58.5acrylonitrile 35.5 glycidyl methacrylate (GMA) 6 Total amount of water220 Texapon ® K-12 2.6 Na₂SO₄ 0.12 pH 7 t-DDM 0.54 Trigonox ® NT 50 0.02Fe(II)SO₄ premix solution 0.026 diethylhydroxylamine 0.2 Wingstay ®29/Naugawhite 0.18 Polymerization temperature [° C.] 8.0 ± 0.5Polymerization conversion [%] 80 Polymerization time [h] 7

The nitrile rubber was produced batchwise in a 5 l autoclave withstirrer system. In the autoclave batch, 1.25 kg of the monomer mixtureand a total amount of water of 2.1 kg were used, as was EDTA in anequimolar amount based on the Fe(II). 1.9 kg of this amount of waterwere initially charged with the emulsifier in the autoclave and purgedwith a nitrogen stream. Thereafter, the destabilized monomers and theamount of the t-DDM molecular weight regulator specified in Table 1 wereadded and the reactor was closed. After the reactor contents had beenbrought to temperature, the polymerizations were started by the additionof the Fe(II)SO₄ premix solution and of para-menthane hydroperoxide(Trigonox® NT50). The course of the polymerization was monitored bygravimetric determinations of conversion. On attainment of theconversion reported in Table 1, the polymerization was stopped by addingan aqueous solution of diethylhydroxylamine. Unconverted monomers andother volatile constituents were removed by means of steam distillation.

The dried NBR rubber was characterized by the Mooney viscosity, the MSRthereof, the ACN content and the glass transition temperature. Thecontent of the termonomer was determined by ¹H NMR analysis. The solidrubber obtained had the properties reported in Tab. 2.

TABLE 2 Properties of nitrile rubber A containing epoxy groups Nitrilerubber A ACN content (%) 32.2 Mooney viscosity ML (1 + 4 at 100° C.)(Mu) 31 MSR (Mu/s) 0.671 Termonomer incorporated (% by wt.) 4.7 Glasstransition temperature T_(G) (° C.) −25.1

II Production of Vulcanizates of Nitrile Rubber Terpolymer A(Comparative Example V1 and Inventive Examples V2-V4)

The nitrile rubber terpolymer A was used as described below to producevulcanizates V1 to V4. The constituents of the vulcanizable mixtures arebased on 100 parts of rubber and are reported in Tables 3 and 7.

The mixtures were produced in a Banbury Mixer. For this purpose, in eachcase, the rubber and all additives specified in Tables 3 and 7 weremixed at a maximum temperature of up to 120° C. for a total of 4minutes. For this purpose, the rubber was initially charged in themixer, all further additives were added after 1 minute, and after 2further minutes a reversal step was conducted. After a total of 4minutes, the rubber was discharged from the mixer. The compound wasvulcanized sit the temperatures specified.

Vulcanizate V1 obtained had the properties reported in Tables 4 to 6;vulcanizates V2-V4 had the properties reported in tables 8 to 10:

TABLE 3 Composition of the vulcanizable mixture for vulcanizate V1(Comparative Example) Vulcanizable mixture for V1 Polymer A 100 CORAX ®N 550/30 50 DIPLAST ® TM 8-10/ST 5 VULKANOX ZMB2/C5 0.4 LUVOMAXX CDPA 1Lupragen N 700 4 Total phr 160.4 Density g/ccm 1.137

TABLE 4 Vulcanizate V1; vulcanization profile in the MDR (190° C./30minutes) Vulcanizate V1 S max (dNm) 25.2 t₁₀ (min) 0.6 t₉₅ (min) 19.0

TABLE 5 Vulcanizate V1, properties Vulcanizate V1 Crosslinkingtemperature C. 190 Crosslinking time min 30 TS MPa 18.9 EB % 226 M50 MPa2.6 M100 MPa 6.9 Hardness Shore A 71

TABLE 6 Vulcanizate V1, compression set at 23° C. and 1.50° C.Vulcanizate V1 Temperature and time: 23° C./24 hours CS % 4 Temperatureand time: 150° C./24 hours CS % 33

TABLE 7 Composition of the vulcanizable mixtures for vulcanizates V2 toV4 (Inventive Examples) Vulcanizable mixture for V2 V3 V4 Polymer A 100100 100 CORAX ® N 550/30 50 50 50 DIPLAST ® TM 8-10/ST 5 5 5 VULKANOXZMB2/C5 0.4 0.4 0.4 LUVOMAXX CDPA 1 1 1 Lupragen N 700 4 4 4 VULKACIT PEXTRA N 1 VULCOFAC HDC 1 RHENOCURE SDT/S 1 Total phr 161.4 161.4 161.4Density g/ccm 1.139 1.137 1.137

TABLE 8 Vulcanizates V2 to V4; vulcanization profile in the MDR (190°C./30 minutes) Vulcanizate V2 V3 V4 S max (dNm) 23.1 22.2 22.1 t₁₀ (min)0.3 0.5 0.4 t₉₅ (min) 9.5 10.5 13.0

TABLE 9 Vulcanizates V2 to V4; properties Vulcanizate V2 V3 V4Crosslinking ° C. 190 temperature Crosslinking time min 30 30 30 TS MPa15.4 19.7 16.2 EB % 150 235 163 M50 MPa 3 2.4 2.8 M100 MPa 8.9 6.4 7.7Hardness Shore A 71 69 70

TABLE 10 Vulcanizates V2 to V4; compression set as 23° C. and 150° C.Vulcanizate V2 V3 V4 Temperature and time: 23° C., 24 hours CS % 4 4 3Temperature and time: 150° C., 24 hours CS % 24 33 24

The use of a crosslinking accelerator thus simultaneously allows thecrosslinking time required to vulcanize the rubber mixtures to beshortened and surprisingly, at the same time, the long-term compressionset at 150° C. to be improved.

What is claimed is:
 1. Vulcanizable composition comprising: (i) at leastone optionally fully or partly hydrogenated nitrile rubber containingepoxy groups and comprising repeat units derived from at least oneconjugated diene, at least one α,β-unsaturated nitrile and optionallyone or more further copolymerizable monomers, but not from anonconjugated cyclic polyene; (ii) at least one Lewis base and/or atleast one Brønsted base as a crosslinker, wherein: the at least oneLewis base is selected from the group consisting of crown ethers,cryptands, triphenylphosphine, sodium cyanide, potassium cyanide, sodiumiodide, bipyridine, phenanthroline, tetrahydrofuran, cyclooctadiene,hydrazine and diethyl ether; and the at least one Brønsted base isselected from the group consisting of sulphates, sulphites, sulphides,phosphates, sodium carbonate, potassium carbonate, calcium carbonate,lithium carbonate, triethylamine, diisopropylamine, triethanolamine,pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene,1,4-diazabicyclo[2.2.2]octane, tetramethylenediamine, pyrrolidine,pyrazole, piperidine, pyrrole, imidazole, substituted or unsubstitutedurea derivatives, hydroxides of alkali metals or alkaline earth metals,salts of inorganic or organic sulphonic acids, carboxylic acids andphosphoric acids, the mono- or diesters thereof, and organometalliccompounds of the alkali metals lithium, sodium and potassium; and (iii)at least one crosslinking accelerator selected from the group consistingof thiurams, xanthogenates, dithiocarbamates and carbamates, where theLewis and/or Brønsted base (ii) must be different from the defined groupof crosslinking accelerators (iii), crosslinkers other than thosementioned in (ii) are present in the vulcanizable composition only in anamount of less than 2.5 parts by weight based on 100 parts by weight ofthe optionally fully or partly hydrogenated nitrile rubber (i)containing epoxy groups, and crosslinking accelerators other than thosementioned in (iii) are present only in an amount of less than 2.5 partsby weight based on 100 parts by weight of the optionally fully or partlyhydrogenated nitrile rubber (i) containing epoxy groups.
 2. Thevulcanizable composition according to claim 1, further comprising, basedin each case on 100 parts by weight of the optionally fully or partlyhydrogenated nitrile rubber (i) containing epoxy groups: at least oneadditional crosslinker other than those mentioned in (ii) up to amaximum amount of 2.3 parts by weight, and at least one additionalcrosslinking accelerator other than those mentioned in (iii) up to amaximum amount of 2.3 parts by weight.
 3. The vulcanizable compositionaccording to claim 2, wherein the composition comprises up to a maximumamount of 2.25 parts by weight of the at least one additionalcrosslinker, and, up to a maximum amount of 2.25 parts by weight of theat least one additional crosslinking accelerator.
 4. The vulcanizablecomposition according to claim 2, wherein the composition comprises upto a maximum amount of 2 parts by weight of the at least one additionalcrosslinker, and, up to a maximum amount of 2 parts by weight of the atleast one additional crosslinking accelerator.
 5. The vulcanizablecomposition according to claim 2, wherein the composition comprises upto a maximum amount of 1.5 parts by weight of the at least oneadditional crosslinker, and, up to a maximum amount of 1.5 parts byweight of the at least one additional crosslinking accelerator.
 6. Thevulcanizable composition according to claim 2, wherein the compositioncomprises up to a maximum amount of 1 part by weight of the at least oneadditional crosslinker, and, up to a maximum amount of 1 part by weightof the at least one additional crosslinking accelerator.
 7. Thevulcanizable composition according to claim 2, wherein the compositioncomprises up to a maximum amount of 0.5 parts by weight of the at leastone additional crosslinker, and, up to a maximum amount of 0.5 parts byweight of the at least one additional crosslinking accelerator.
 8. Thevulcanizable composition according to claim 2, wherein the compositioncomprises up to a maximum amount of 0.4 parts by weight of the at leastone additional crosslinker, and, up to a maximum amount of 0.4 parts byweight of the at least one additional crosslinking accelerator.
 9. Thevulcanizable composition according to claim 1, wherein the compositioncomprises: (i) at least one optionally fully or partly hydrogenatednitrile rubber containing epoxy groups and comprising repeat unitsderived from at least one conjugated diene, at least one α,β-unsaturatednitrile and optionally one or more further copolymerizable monomers, butnot from a nonconjugated cyclic polyene; (ii) at least one Lewis baseselected from the group consisting of crown ethers, cryptands,triphenylphosphine, and bipyridine and/or a Brønsted base selected fromthe group consisting of sodium carbonate, potassium carbonate, calciumcarbonate, lithium carbonate, triethylamine, diisopropylamine,triethanolamine, pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene,1,4-diazabicyclo[2.2.2]octane, tetramethylethylenediamine, pyrrolidine,pyrazole, piperidine, pyrrole, imidazole, urea, biuret, dimethylurea,N,N′-dimethylpropyleneurea and sodium dodecylbenzylsulphonate as acrosslinker; (iii) at least one crosslinking accelerator selected fromthe group consisting of hexamethylene diaminocarbamate,tetramethylthiuram disulphide (TMTD), tetramethylthiuram monosulphide(TMTM), tetraethylthiuram disulphide (TETD), dipentamethylenethiurammonosulphide (DPTM), dipentamethylenethiuram disulphide (DPTD),dimethyldiphenylthiuram disulphide (MPTD), arylguanidiniumxanthogenates, zinc isopropylxanthogenate (ZIX), zincdimethyldithiocarbamate (ZDMC), zinc diethyldithiocarbamate (ZDEC), zincdibutyldithiocarbamate (ZDBC), zinc ethylphenyldithiocarbamate (ZEPC),zinc dibenzyldithiocarbamate (ZDBC), zinc pentamethylenedithiocarbamate(ZPD), sodium diethyldithiocarbamate (SEDC), sodiumdimethyldithiocarbamate (SMDC), sodium dibutyldithiocarbamate (SBC) andsodium cyclohexylethyldithiocarbamate (SHEC), at least one additionalcrosslinker other than those mentioned in (ii) in an amount of less than2.5 parts by weight, based on 100 parts by weight of the optionallyfully or partly hydrogenated nitrile rubber (i) containing epoxy groups,and at least one additional crosslinking accelerator other than thosementioned in (iii) in an amount of less than 2.5 parts by weight, basedon 100 parts by weight of the optionally fully or partly hydrogenatednitrile rubber (i) containing epoxy groups.
 10. The vulcanizablecomposition according to claim 1, wherein the optionally fully or partlyhydrogenated nitrile rubber (i) containing epoxy groups is one in whichthe epoxy groups are applied to the nitrile rubber by subsequentgrafting of compounds containing epoxy groups, or else one having repeatunits of at least one nitrile, of at least one conjugated diene, of atleast one monomer containing epoxy groups, and optionally of one or morefurther copolymerizable monomers, but none of any nonconjugated cyclicpolyenes.
 11. The vulcanizable composition according to claim 1, whereinthe fully or partly hydrogenated nitrile rubber (i) containing epoxygroups has repeat units of a monomer which contains epoxy groupsselected from the group consisting of o-vinylbenzylglycidyl ether,m-vinylbenzylglycidyl ether, p-vinylbenzylglycidyl ether,3-vinylcyclohexene oxide, and monomers of the general formula (I)

In which M is 0 or 1 and X is O,O(CR₂)_(p), (CR₂)_(p) or, C(═O)O,C(═O)O(CR₂)_(p), C(═O)NR, (CR₂)_(p), N(R), N(R)(CR₂)_(p), P(R),P(R)(CR₂)_(p), P(═O)(R), P(═O)(R)(CR₂)_(p) S, S(CR₂)_(p), S(═O),S(═O)(CR₂)_(p), S(═O)₂(CR₂)_(p) o S(═O), where R in these radicals maybe as defined for R¹-R⁶, Y represents repeat units of one or more mono-or polyunsaturated monomers, comprising conjugated or nonconjugateddienes, alkynes and vinyl compounds, or a structural element whichderives from polymers comprising polyethers, polysiloxanes, polyols,polycarbonates, polyurethanes, polyisocyanates, polysaccharides,polyesters and polyamides, n and p are the same or different and areeach in the range from 0 to 10 000, R, R¹, R², R³, R⁴, R⁵ and R⁶ are thesame or different and are each H, a linear or branched, saturated ormono- or polyunsaturated alkyl radical, a saturated or mono- orpolyunsaturated carbo- or heterocyclyl radical, aryl, heteroaryl,arylalkyl, heteroarylalkyl, alkoxy, aryloxy, heteroaryoxy, amino, amido,carbamoyl, alkylthio, arylthio, sulphanyl, thiocarboxyl, sulphinyl,sulphono, sulphino, sulpheno, sulphonic acids, sulphamoyl, hydroxyimino,alkoxycarbonyl, F, Cl, Br, I, hydroxyl, phosphonato, phosphinato, silyl,silyloxy, nitrile, borates, selenates, carbonyl, carboxyl, oxycarbonyl,oxysulphonyl, oxo, thioxo, epoxy, cyanates, thiocyanates, isocyanates,thioisocyanates or isocyanides.
 12. The vulcanizable compositionaccording to claim 1 wherein the fully or partly hydrogenated nitrilerubber (i) containing epoxy groups has repeat units of a monomer whichcontains epoxy groups and is selected from the group consisting of2-ethylglycidyl acrylate, 2-ethylglycidyl methacrylate,2-(n-propyl)glycidyl acrylate, 2-(n-propyl)glycidyl methacrylate,2-(n-butyl)glycidyl acrylate, 2-(n-butyl)glycidyl methacrylate, glycidylmethacrylate, glycidylmethyl methacrylate, glycidyl acrylate,(3′,4′-epoxyheptyl)-2-ethyl acrylate, (3′,4′-epoxyheptyl)-2-ethylmethacrylate, 6′,7′-epoxyheptyl acrylate, 6′,7′-epoxyheptylmethacrylate, allyl glycidyl ether, allyl 3,4-epoxyheptyl ether,6,7-epoxyheptyl allyl ether, vinyl glycidyl ether, vinyl 3,4-epoxyheptylether, 3,4-epoxyheptyl vinyl ether, 6,7-epoxyheptyl vinyl ether,o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether,p-vinylbenzyl glycidyl ether and 3-vinylcyclohexene oxide.
 13. Thevulcanizable composition according to claim 1, wherein the compositioncomprises: (i) at least one optionally fully or partly hydrogenatednitrile rubber containing epoxy groups and comprising repeat unitsderived from a) acrylonitrile, b) 1,3-butadiene, c) at least one monomerwhich contains epoxy groups and is selected from the group consisting of2-ethylglycidyl acrylate, 2-ethylglycidyl methacrylate,2-(n-propyl)glycidyl acrylate, 2-(n-propyl)glycidyl methacrylate,2-(n-butyl)glycidyl acrylate, 2-(n-butyl)glycidyl methacrylate, glycidylmethacrylate, glycidylmethyl methacrylate, glycidyl acrylate,(3′,4′-epoxyheptyl)-2-ethyl acrylate, (3′,4′-epoxyheptyl)-2-ethylmethacrylate, 6′,7′-epoxyheptyl acrylate, 6′,7′-epoxyheptylmethacrylate, allyl glycidyl ether, allyl 3,4-epoxyheptyl ether,6,7-epoxyheptyl allyl ether, vinyl glycidyl ether, vinyl 3,4-epoxyheptylether, 3,4-epoxyheptyl vinyl ether, 6,7-epoxyheptyl vinyl ether,o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether,p-vinylbenzyl glycidyl ether and 3-vinylcyclohexene oxide, and d)optionally one or more further copolymerizable monomers, but not from anonconjugated cyclic polyene; (ii) at least one Lewis base selected fromthe group consisting of crown ethers, cryptands, and triphenylphosphineand/or a Brønsted base selected from the group consisting of sodiumcarbonate, potassium carbonate, lithium carbonate,1,8-diazabicyclo[5.4.0]undec-7-ene, 1,4-diazabicyclo[2.2.2]octane,pyrrolidine, pyrazole, imidazole, urea, biuret, dimethylurea,N,N′-dimethylpropyleneurea and sodium dodecylbenzylsulphonate as acrosslinker; and (iii) at least one crosslinking accelerator selectedfrom the group consisting of hexamethylene diaminocarbamate,tetramethylthiuram disulphide (TMTD), tetramethylthiuram monosulphide(TMTM), tetraethylthiuram disulphide (TETD), dipentamethylenethiuramdisulphide (DPTD), zinc isopropylxanthogenate (ZIX), zincdimethyldithiocarbamate (ZDMC), zinc diethyldithiocarbamate (ZDEC), zincdibutylthiocarbamate (ZDBC), zinc ethylphenyldithiocarbamate (ZEPC),zinc pentamethylenedithiocarbamate (ZPD), sodium diethyldithiocarbamate(SEDC) and sodium cyclohexylethyldithiocarbamate (SHEC), at least oneadditional crosslinker other than those mentioned in (i) in an amountless than 2.5 parts by weight, based on 100 parts by weight of theoptionally fully or partly hydrogenated nitrile rubber (i) containingepoxy groups, and at least one additional crosslinking accelerator otherthan those mentioned in (iii) in an amount of less than 2.5 parts byweight based on 100 parts by weight of the optionally fully or partlyhydrogenated nitrile rubber (i) containing epoxy groups.
 14. Thevulcanizable composition according to claim 1, wherein the compositioncomprises: (i) at least one optionally fully or partly hydrogenatednitrile rubber containing epoxy groups and comprising repeat unitsderived from a) acrylonitrile, b) 1,3-butadiene, c) glycidyl acrylateand/or glycidyl methacrylate, and d) optionally one or more furthercopolymerizable monomers, but not from a nonconjugated cyclic polyene;(ii) at least one Lewis base selected from the group consisting of crownethers, cryptands, and triphenylphosphine and/or a Brønsted baseselected from the group consisting of sodium carbonate, potassiumcarbonate, lithium carbonate, 1,8-diazabicyclo[5.4.0]undec-7-ene,1,4-diazabicyclo[2.2.2]octane, pyrrolidine, pyrazole, imidazole, urea,biuret, dimethylurea, N,N′-dimethylpropyleneurea and sodiumdodecylbenzylsulphonate as a crosslinker; and (iii) at least onecrosslinking accelerator selected from the group consisting ofhexamethylene diaminocarbamate, tetramethylthiuram disulphide (TMTD),tetramethylthiuram monosulphide (TMTM), tetraethylthiuram disulphide(TETD), dipentamethylenethiuram disulphide (DPTD), zincisopropylxanthogenate (ZIX), zinc dimethyldithiocarbamate (ZDMC), zincdiethyldithiocarbamate (ZDEC), zinc dibutyldithiocarbamate (ZDBC), zincethylphenyldithiocarbamate (ZEPC), zinc pentamethylenedithiocarbamate(ZPD), sodium diethyldithiocarbamate (SEDC) and sodiumcyclohexylethyldithiocarbamate (SHEC), at least one additionalcrosslinker other than those mentioned in (ii) in an amount less than2.5 parts by weight, based on 100 parts by weight of the optionallyfully or partly hydrogenated nitrile rubber (i) containing epoxy groups,and at least one additional crosslinking accelerator other than thosementioned in (iii) in an amount of less than 2.5 parts by weight, basedon 100 parts by weight of the optionally fully or partly hydrogenatednitrile rubber (i) containing epoxy groups.
 15. A process for producingthe vulcanizable composition according to claim 1, the processcomprising mixing the at least one fully or partly hydrogenated nitrilerubber (i) with the at least one Lewis base and/or the at least oneBrønsted base (ii) and the at least one crosslinking accelerator (iii).16. A process for producing vulcanizates based on an optionally fully orpartly hydrogenated nitrile rubber containing epoxy groups, the processcomprising crosslinking the vulcanizable composition according to claim1 with increasing temperature.
 17. Vulcanizates based on a crosslinked,optionally fully or partly hydrogenated nitrile rubber containing epoxygroups according to claim
 1. 18. The vulcanizable composition accordingto claim 1, wherein the composition contains no additional crosslinkersother than those mentioned in (ii) and no additional crosslinkingaccelerators other than those mentioned in (iii).